chore: repo review fixes — lint, CI, doc currency, organization

[mmcky]

Addresses findings from a deep technical review of the repo (code quality, docs, organization). No behavioral/source-logic changes to the action or CLI.

Code quality & CI

• Lint is now clean (npm run lint → 0 errors). Removed unused imports in review-formatter.ts, typed normalizeVerdict's param in forward-triage.ts, and fixed Object types / a stray let in tests.
• Added an eslint overrides block relaxing no-explicit-any / no-unused-vars for test files.
• Added .github/workflows/ci.yml — runs lint, build, and tests on every PR, plus a guard that fails if the committed dist-action/ bundle is stale (the classic "forgot to rebuild the action" bug). Previously nothing enforced tests in CI.

Documentation currency

• README header: v0.11.2 → v0.15.0, tests 909 → 1005.
• Replaced the nonexistent npm run package command with npm run build across README + docs, and corrected the build-pipeline description in architecture.md (build does tsc compile and esbuild bundle).
• Updated stale test counts (724/909 → 1005) and version stamps in developer docs.
• Pointed all action usage examples at the floating @v0 tag instead of the outdated @v0.11 (16 references).
• Fixed broken links in glossary/README.md (docs/BUILT-IN-GLOSSARY.md → docs/user/glossary.md; ../CONTRIBUTING.md now resolves).

Organization

• Moved PLAN.md and FIX-ISSUE-63.md out of the repo root into dev-notes/ (with a README); updated references in copilot-instructions.md and docs/projects/README.md. Kept out of the published docs/ site.
• Added CONTRIBUTING.md.

Verification

• npm run lint → 0 errors (13 pre-existing warnings remain)
• npm test → 1005 tests, 39 suites, all passing
• npm run build → clean; dist-action/ unchanged after rebuild

🤖 Generated with Claude Code

[Copilot]

Pull request overview

Maintenance-focused PR to improve repo hygiene for action-translation (a GitHub Action + CLI), primarily addressing lint/CI gaps and bringing documentation/organization in sync with the current build pipeline and release version—without changing action/CLI behavior.

Changes:

• Add PR CI (lint/build/test) and a guard to ensure the committed dist-action/ bundle is not stale.
• Clean up lint/type issues in a few TS files and relax certain ESLint rules for test files via overrides.
• Update docs for current version/test counts and correct build instructions; reorganize internal notes under dev-notes/ and add CONTRIBUTING.md.

Reviewed changes

Copilot reviewed 21 out of 23 changed files in this pull request and generated 2 comments.

Show a summary per file

File	Description
src/cli/review-formatter.ts	Removes unused imports to keep lint clean.
src/cli/forward-triage.ts	Tightens typing for parsed triage responses.
src/tests/translator-retry.test.ts	Replaces Object typing with unknown in mocked SDK errors.
src/tests/integration.test.ts	Replaces an unnecessary let with const in a test.
README.md	Updates version/test counts and corrects build instructions + action version tag in examples.
glossary/README.md	Fixes glossary documentation link target.
docs/user/tutorials/fresh-setup.md	Updates action usage examples to @v0.
docs/user/tutorials/connect-existing.md	Updates action usage examples to @v0.
docs/user/tutorials/add-language.md	Updates action usage examples/build instructions (but currently repeats npm run build).
docs/user/quickstart.md	Updates action usage examples to @v0.
docs/user/language-config.md	Replaces obsolete npm run package guidance with npm run build.
docs/user/glossary.md	Updates action usage examples to @v0.
docs/user/action-reference.md	Updates action usage examples to @v0.
docs/projects/README.md	Updates PLAN link to new dev-notes/ location.
docs/developer/testing.md	Updates test counts/suite counts.
docs/developer/architecture.md	Updates build pipeline documentation and current version stamp.
dev-notes/README.md	Introduces a pointer/index for internal maintainer notes.
dev-notes/PLAN.md	Moves the roadmap document under dev-notes/.
dev-notes/FIX-ISSUE-63.md	Moves the historical issue write-up under dev-notes/.
CONTRIBUTING.md	Adds contributor workflow documentation and dist-action rebuild guidance.
.github/workflows/ci.yml	Adds CI workflow for lint/build/test + dist-action freshness check.
.github/copilot-instructions.md	Updates release checklist references to dev-notes/PLAN.md.
.eslintrc.json	Adds test-file overrides for no-explicit-any / no-unused-vars.