test: add compatibility matrix and evidence fixtures

[shenjiecode]

Summary

• add minimum/current/latest Pi host compatibility coverage on Node 22/24
• add deterministic evidence golden fixtures and replay tests
• consume @cynos-ai/tools@0.3.0 with optional playwright-core
• keep ordinary Engineer installs free of the Playwright runtime
• add packed-package protection against accidentally bundling optional Playwright

Verification

• npm run verify (404 tests)
• minimum Pi 0.84.2 local compatibility run
• packed package smoke with bundled Tools 0.3.0 and no Playwright installed
• npm run pack:dry-run (about 982 KiB unpacked)
• npm audit --omit=dev --audit-level=high
• compatibility workflow YAML parse

External-content injection security tests are intentionally out of scope for this change.