fix(mcp): bundle docs server in package

[crup]

Bundles the optional MCP docs server into the published package so users can run it from npm instead of the source repository.

Changes:

• Adds a minified Node build at dist/mcp/server.js.
• Adds the npm bin react-timer-hook-mcp.
• Adds a package export for ./mcp/server.
• Makes the MCP server self-contained instead of reading docs-site/static/llms-full.txt from the source repo.
• Adds pnpm mcp:check and runs it in CI and the stable release verify stage.
• Updates README and docs with npx and node_modules/.bin MCP client config.
• Adds MCP docs server to the size report.

Validation run locally:

• pnpm typecheck
• pnpm test
• pnpm build
• pnpm docs:build
• pnpm readme:check
• pnpm mcp:check
• pnpm size
• pnpm pack --dry-run
• git diff --check

Release note:

• npm latest is already 0.0.2, so this should publish as 0.0.3 after merge.

[github-actions]

Bundle size report

Entry	Files	Raw	Gzip	Brotli	Raw delta	Gzip delta	Brotli delta
core	2	4.44 kB	1.52 kB	1.40 kB	0 B	0 B	0 B
timer group add-on	3	10.93 kB	3.83 kB	3.50 kB	0 B	0 B	0 B
schedules add-on	3	8.62 kB	3.02 kB	2.78 kB	0 B	0 B	0 B
duration helper	1	318 B	224 B	192 B	0 B	0 B	0 B
diagnostics helper	1	105 B	115 B	90 B	0 B	0 B	0 B
MCP docs server	1	3.80 kB	1.63 kB	1.40 kB	+3.80 kB	+1.63 kB	+1.40 kB
core CJS	1	4.71 kB	1.63 kB	1.50 kB	0 B	0 B	0 B
timer group CJS	1	11.02 kB	3.86 kB	3.54 kB	0 B	0 B	0 B
schedules CJS	1	8.71 kB	3.04 kB	2.81 kB	0 B	0 B	0 B
duration CJS	1	808 B	475 B	424 B	0 B	0 B	0 B
diagnostics CJS	1	605 B	367 B	326 B	0 B	0 B	0 B