CI paths: Python Lint — add self-trigger path #843

Part of #834. Phase 1 (unanchored corrections — no dependency on any other slice).

What

python-lint.yml filters on packages/python/**/*.py and packages/python/pyproject.toml, but does not name its own file. Editing the workflow does not run it. Spec row 16 requires a workflow file to trigger its own workflow.

Exact change

.github/workflows/python-lint.yml — replace the on: block with:

on:
  push:
    branches: [main]
    paths:
      - 'packages/python/**/*.py'
      - 'packages/python/pyproject.toml'
      - '.github/workflows/python-lint.yml'
  pull_request:
    paths:
      - 'packages/python/**/*.py'
      - 'packages/python/pyproject.toml'
      - '.github/workflows/python-lint.yml'

Only the two paths: lists change. Do not touch the jobs.

Expected checks on this PR

Files touched: .github/workflows/python-lint.yml only.

MUST run

• Python Lint — this is the whole point; it proves the self-path took effect. It did not run on this PR's first push if you push the workflow edit as the only commit — it does run, because pull_request triggers are read from the PR head branch, so the new filter applies to the PR that introduces it.

MUST NOT run

• Python Test, TS Test, Rust Test, Plugins Test, Python Typecheck, TS Lint, TS Typecheck — every one is already path-filtered and none names python-lint.yml.

May still run (not yet filtered — expected noise until phases 2–4 land)

• Conventions (all 8 lanes), Release Precheck, Release Config Check, Changelog Check

Acceptance

• The PR's check list matches the three groups above exactly
• Mergify Merge Protections green
• Merge, close this issue

Notes

• No changelog fragment required (no packages/** change).
• No e2e attestation refresh required.
• Not anchored in .mergify.yml, so this slice does not depend on Epic — CI: run only the checks relevant to the changed paths #834's Mergify work and can land immediately.