feat: expose cache facts in json output

[bntvllnt]

Summary

• add top-level cache facts to analysis command JSON output and init --json
• expose CacheFacts in shared types and document the JSON contract
• add E2E coverage for canonical, migrated legacy, ignored legacy warning, and init --gitignore JSON facts
• harden pnpm test against Vitest duration-cache ordering and host memory pressure
• update real-repo verifier to allow only top-level documented cache paths

Gates

• pnpm exec eslint src/cli.ts src/persistence/index-dir.ts src/types/index.ts tests/index-directory.test.ts tests/cli-cache.e2e.test.ts tests/cli-init.e2e.test.ts
• pnpm lint
• pnpm typecheck
• pnpm build
• pnpm test (28 files, 431 tests)
• pnpm verify:cli-real (pass=56 fail=0)

Review

• codebase-intelligence changes/hotspots/dependents/impact/dead-exports ran
• react-doctor not applicable: no React files changed
• code-review verdict: clean

Canary

• 2.5.0 canary train only; no stable release in this PR