fix(ci,docs): use unittest discovery for scripts.tests and align the-walk default route

[gcko]

Implements DRC-4557 - The platform-tests job runs a third hand-kept scripts.tests list that has drifted from the other two
Implements DRC-4549 - the-walk.md says #n=sessions is the default route; the board opens at #n=projects

Summary

1. DRC-4557: Replace hand-enumerated scripts.tests.* module lists in .github/workflows/quality-gate.yml (runtime-floor, test, and platform-tests) and AGENTS.md with python -m unittest discover -s scripts/tests -t scripts/tests.
   • Runs all 13 test modules automatically on Linux, macOS, and Windows.
   • Eliminates structural drift between workflow files and local pre-PR checks.
   • Adds ScriptTestsDiscoveryContractTest in scripts/tests/test_validate_plugins.py to assert discovery coverage and prevent regression to hand-kept lists.
2. DRC-4549: Update .claude/skills/visual-review-and-fix/references/the-walk.md routes section to state that #n=projects is the default route per NUI-16 in docs/design-next-ui.md, and #n=sessions is fleet operations.

Verification

• python3 -m unittest scripts.tests.test_validate_plugins.ScriptTestsDiscoveryContractTest (2 tests, pass)
• Full coverage run with discovery:
  coverage run -m unittest discover -s cargento/skills/cargento/tests -t .
coverage run -a -m unittest discover -s scripts/tests -t scripts/tests
coverage report (86.8% coverage, pass)
• Full static gate (ruff check ., ruff format --check ., mypy, lint_embedded.py, validate_plugins.py, bump_version.py) passed cleanly.

[github-actions]

Coverage

Name                                                                  Stmts   Miss Branch BrPart  Cover
-------------------------------------------------------------------------------------------------------
cargento/skills/cargento/agy_hook.py                                     79     14     28      7  78.5%
cargento/skills/cargento/cargento_runtime/__init__.py                     0      0      0      0 100.0%
cargento/skills/cargento/cargento_runtime/aggregate.py                  323      3    110      3  98.6%
cargento/skills/cargento/cargento_runtime/annotations.py                373     19    130     21  92.0%
cargento/skills/cargento/cargento_runtime/asks.py                       110      0     28      0 100.0%
cargento/skills/cargento/cargento_runtime/claude_data.py                340     40    158     18  88.4%
cargento/skills/cargento/cargento_runtime/cli.py                        212     20     52      6  89.4%
cargento/skills/cargento/cargento_runtime/collectors/__init__.py          0      0      0      0 100.0%
cargento/skills/cargento/cargento_runtime/collectors/antigravity.py     423     41    174     25  87.3%
cargento/skills/cargento/cargento_runtime/collectors/claude.py          305     17    112     15  91.8%
cargento/skills/cargento/cargento_runtime/collectors/codex.py           258     18     96     15  90.7%
cargento/skills/cargento/cargento_runtime/collectors/copilot.py         153      4     52      2  97.1%
cargento/skills/cargento/cargento_runtime/collectors/cursor.py          287     19    108     16  90.6%
cargento/skills/cargento/cargento_runtime/collectors/droid.py            34      3      6      1  90.0%
cargento/skills/cargento/cargento_runtime/collectors/gemini.py           54      7     16      4  84.3%
cargento/skills/cargento/cargento_runtime/collectors/goose.py            95      6     28      4  91.9%
cargento/skills/cargento/cargento_runtime/collectors/opencode.py        124      4     44      4  95.2%
cargento/skills/cargento/cargento_runtime/collectors/pi.py              328     34    152     20  88.8%
cargento/skills/cargento/cargento_runtime/config.py                     232      1     20      1  99.2%
cargento/skills/cargento/cargento_runtime/deliveries.py                 128     12     30      7  88.0%
cargento/skills/cargento/cargento_runtime/departures.py                 131      6     30      6  92.5%
cargento/skills/cargento/cargento_runtime/diagnostics.py                 88      3     26      3  94.7%
cargento/skills/cargento/cargento_runtime/dismissals.py                 111      3     32      3  95.8%
cargento/skills/cargento/cargento_runtime/ends.py                        89      5     18      0  95.3%
cargento/skills/cargento/cargento_runtime/events.py                     230      1     86      3  98.7%
cargento/skills/cargento/cargento_runtime/focus.py                       72      2     20      2  95.7%
cargento/skills/cargento/cargento_runtime/git_status.py                  59      1     22      2  96.3%
cargento/skills/cargento/cargento_runtime/history.py                    206      9     56      7  93.9%
cargento/skills/cargento/cargento_runtime/http_api.py                   933    107    300     37  88.3%
cargento/skills/cargento/cargento_runtime/interaction_prototype.py      709    221    198     38  65.7%
cargento/skills/cargento/cargento_runtime/io.py                         163      2     38      1  98.5%
cargento/skills/cargento/cargento_runtime/irreversible.py                39      0      6      0 100.0%
cargento/skills/cargento/cargento_runtime/lifecycle.py                  412     47    140     14  87.5%
cargento/skills/cargento/cargento_runtime/notifications.py              264     12     92      7  94.7%
cargento/skills/cargento/cargento_runtime/observation.py                412      6    122      3  98.3%
cargento/skills/cargento/cargento_runtime/observer.py                   388     24    156     15  92.8%
cargento/skills/cargento/cargento_runtime/probe.py                       44      0     18      1  98.4%
cargento/skills/cargento/cargento_runtime/project_context.py           1588    179    686    121  85.3%
cargento/skills/cargento/cargento_runtime/quota.py                      392      7    144      6  97.2%
cargento/skills/cargento/cargento_runtime/reach.py                       78      6     30      4  90.7%
cargento/skills/cargento/cargento_runtime/reading.py                    365      7    122      6  97.3%
cargento/skills/cargento/cargento_runtime/records.py                    265      5    118      9  96.3%
cargento/skills/cargento/cargento_runtime/semantic_history.py           290     14    110     18  92.0%
cargento/skills/cargento/cargento_runtime/sessions.py                   189      4     72      4  96.9%
cargento/skills/cargento/cargento_runtime/snapshot.py                    36      0      4      0 100.0%
cargento/skills/cargento/cargento_runtime/spacedock.py                  510     50    260     26  89.9%
cargento/skills/cargento/cargento_runtime/state.py                       83      0      2      0 100.0%
cargento/skills/cargento/cargento_runtime/stream.py                      57      0      8      0 100.0%
cargento/skills/cargento/cargento_runtime/transcripts.py                529     29    272     25  93.3%
cargento/skills/cargento/cargento_runtime/tripwires.py                  232     14     94     13  91.7%
cargento/skills/cargento/cargento_runtime/turns.py                      209     11    104     12  92.7%
cargento/skills/cargento/cargento_runtime/unasked.py                    119      2     34      1  98.0%
cargento/skills/cargento/cargento_runtime/web/__init__.py                 0      0      0      0 100.0%
cargento/skills/cargento/cargento_runtime/web/page.py                    38      0     10      0 100.0%
cargento/skills/cargento/event_hook.py                                  213     54     92     14  68.5%
cargento/skills/cargento/mcp_server.py                                  377     22    112     14  92.2%
cargento/skills/cargento/notify_hook.py                                  49     15      6      1  67.3%
cargento/skills/cargento/server.py                                        3      0      2      1  80.0%
cargento/skills/cargento/statusline_hook.py                             131     13     46      8  87.0%
scripts/bench_collect.py                                                214     13     54      6  92.9%
scripts/bench_event_latency.py                                           67     21     14      1  67.9%
scripts/bump_version.py                                                  60     12     24      5  77.4%
scripts/capture_focus_raise.py                                          729    131    236     16  79.4%
scripts/capture_hook.py                                                 292     30     90     11  88.7%
scripts/capture_team_registry.py                                        172     33     48      6  80.5%
scripts/capture_terminal_identity.py                                    347    108    104     14  66.3%
scripts/derive_prompt_shapes.py                                         210     16     88     14  89.3%
scripts/lint_embedded.py                                                 97      3     32      3  95.3%
scripts/mark_abstention.py                                              382    142    140     23  58.4%
scripts/score_abstention.py                                             493     52    182     18  88.4%
scripts/serve_operator_cockpit.py                                       448    191    112     20  54.5%
scripts/validate_plugins.py                                             762    202    434     67  70.8%
-------------------------------------------------------------------------------------------------------
TOTAL                                                                 18234   2097   6590    798  86.6%

Threshold: fail_under in pyproject.toml · label coverage-exception to bypass (visible in PR timeline).