fix: harden context ranking and release v0.5.1

[aryamthecodebreaker]

What changed

• fixes context ranking regressions exposed by a frozen six-repository external benchmark
• makes exact path evidence win, maps build-output paths back to TypeScript sources, preserves seed priority through imports, and caps proximity boosts below direct evidence
• adds small priors against examples and declaration files for runtime tasks
• adds focused ranking regressions and grows core coverage to 44 tests
• records exact external top-five outputs and fails scheduled/release evaluation on result drift
• adds a root GitHub Action entrypoint while retaining the nested metadata for compatibility
• prepares v0.5.1 packages, changelog, curated release notes, docs, and an evidence-based 5,000-star launch kit

Measured result

Frozen external benchmark, before → after:

• Top-1: 33.3% (2/6) → 50.0% (3/6)
• Top-3: 33.3% (2/6) → 83.3% (5/6)
• Top-5: 66.7% (4/6) → 83.3% (5/6)

The remaining Zod miss is documented rather than hidden or relabeled.

Internal benchmark: Top-1 62.5% (5/8), Top-3 87.5% (7/8).

Verification

• npm run ci
• Action 5 tests, CLI 41 tests, Core 44 tests
• typecheck, lint, production build, bundle-drift checks, CLI/Action/workspace smoke tests
• node scripts/evaluate-external.mjs --gate --check-recorded
• core and CLI npm pack --dry-run
• root/nested Action metadata synchronization
• v0.5.1 package/dependency/lock/MCP metadata validation
• independent ranking, release-integrity, and upstream-truth reviews: no remaining blockers

Release note

This makes the repository eligible for GitHub Marketplace listing through its root action.yml; actual Marketplace publication remains an owner-side release UI step and is not claimed here.