Rename load_skill to skills_load (CL-6455)

[TheGreatAxios]

CL-6455: models calling skills_load got a grant-denial (tool:.../skills_load/invoke) and retried instead of getting an unknown-tool result or a successful load — the tool was named load_skill, breaking the skills_list / skills_search / skills_* naming pattern models were following.

The first pass at this fixed it by aliasing skills_load to load_skill: a fourth tool definition on the same bundle, and therefore a second invoke grant for one capability. That shape was rejected — one tool should mean one grant, not two names sharing a capability.

This rework is a straight rename instead: the tool is skills_load, consistent with skills_list / skills_search. load_skill no longer exists — no alias, no fallback, per this repo's "no fallbacks" rule. A model still calling the old name now gets the bundle's unknown-tool error result, not a grant denial.

Changed:

• packages/tools-skills: LOAD_SKILL_TOOL → SKILLS_LOAD_TOOL, definition/description/run-switch updated, alias definition and alias test removed.
• packages/skills/src/prompt.ts: the <available_skills> system-prompt stanza now tells models to call skills_load.
• packages/agent-directory, apps/hub/src/skills-mount.ts: comments referencing the old tool name updated.
• packages/tool-registry-publish/src/describe.test.ts: asserts only @corbits/tools-skills/skills:skills_load is minted, and load_skill is not.
• packages/mocks: the hallucinated-tool-name fixture flips — skills_load is now real, so the plausible-but-nonexistent name a model might still guess is load_skill.

Fixes CL-6455

[TheGreatAxios]

Fixes CL-6455

[TheGreatAxios]

Self-review

Verdict: the alias is implemented correctly end-to-end (tool definition, run() dispatch, grant minting via describeCorbitsToolPackages, version bump, and tests) — no defects found, nothing to fix.

• CONFIRMED-OPEN: none.
• DISMISSED: grant-minting path checked directly in describe.ts — each bundle definitions entry (including skills_load) gets its own qualifiedId, so describeCorbitsToolPackages mints a matching tool:.../skills_load grant automatically; the new describe.test.ts case confirms both qualifiedIds are present. No exactOptionalPropertyTypes, bare-catch, as T, or fallback-path issues in the diff.
• DISMISSED: version bump (0.0.1 -> 0.0.2) and its two pin-literal call sites are consistent; check:tool-package-pins and check:tool-package-freshness both pass.

Targeted tests run (all pass):

• packages/tools-skills: bun test src/tool.test.ts (11 pass)
• packages/tool-registry-publish: bun test src/describe.test.ts (5 pass)
• packages/mocks: bun test src/ollama/scenarios.test.ts (10 pass)
• packages/agent-directory: bun test test/routes.test.ts -t "indexes its pinned skills" (1 pass)
• bun run typecheck (repo root): clean

[linear-code]

CL-6455