docs: update for alpha.9 — cache.key docs and resource-lifecycle example

[mahyarmlk]

Summary

Updates docs and resource-lifecycle example for alpha.9 which ships resource cache phase 2 (cache.key).

Changes

README.md:

• Update alpha.8 references → alpha.9 in install commands and version text
• Add cache.key/ResourceKey to capabilities list
• Update limitations from phase 1 to phase 2

docs/Quickstart.md:

• Update install commands from alpha.8 → alpha.9

docs/agent/RELEASE-STATE.md:

• Update version table to reflect alpha.9 for all published packages

examples/resource-lifecycle/src/ResourceDemo.ts:

• Add keyedTeam resource with cache: { key: ({ route }) => route.params.id }
• Add actions for key switching (loadKeyedTeamB, reloadKeyedTeam)

examples/resource-lifecycle/src/ResourceDemo.test.ts:

• 4 new cache.key tests:
  • Keyed resource derives value from route context
  • Different keys are independent
  • Switching active key updates visible value/status
  • No-arg reload reuses last active key
• Update inspectScreen resource count from 5 to 6

Validation

• ✅ pnpm test — all 428 tests pass
• ✅ pnpm typecheck — clean
• ✅ pnpm build — clean
• ✅ pnpm lint — clean
• ✅ pnpm pack:check — clean
• ✅ pnpm changeset status — no changesets needed

Docs/example-only PR — merge when green.