Enforce test coverage on every code change (framework + scaffolded apps)

[vivek7405]

Problem

A code change can ship with unit tests only and miss the browser / e2e / smoke layers it actually needs. This happened with the link-prefetch feature (#152): it is fundamentally browser behaviour (hover issues a speculative fetch, the click consumes a warm cache) yet initially shipped with unit tests alone. Skill descriptions and AGENTS.md prose are advisory; only a deterministic gate keeps every change honest about its test layers.

Design / approach

Two parts.

(A) Framework repo.

• .claude/hooks/require-tests-with-src.sh, a PreToolUse(Bash) hook that BLOCKS a git commit staging packages/*/src/** with no accompanying test file, and BLOCKS a commit that net-removes test lines (the tests-trimmed-to-pass guard). Escape hatches: WEBJS_NO_TEST_GATE=1 and WEBJS_ALLOW_TEST_REMOVAL=1. For client-facing source it also injects a layer reminder (unit is necessary but not sufficient; confirm browser/e2e).
• AGENTS.md "Definition of done" rewrite: the test bullet becomes an explicit per-layer checklist (unit / browser / e2e / smoke) stating that a unit test alone is insufficient for client-router / component / browser-facing changes.

(B) Scaffolded apps (end users). Most webjs users develop with an AI agent, so the gate must reach their apps too. Ship the same enforcement via packages/cli/templates/: wire it into the scaffold .claude/settings.json, the universal .hooks/pre-commit, and the scaffold AGENTS.md / CONVENTIONS.md. Add a test/scaffolds/ assertion that a freshly scaffolded app contains the gate.

Acceptance criteria

• Framework hook blocks a commit staging packages/*/src/** with no test, and a commit that net-removes test lines; both overrides work
• AGENTS.md "Definition of done" spells out the unit / browser / e2e / smoke layers
• Scaffold templates carry the same gate (settings, pre-commit, AGENTS/CONVENTIONS)
• A test/scaffolds/ test asserts a freshly scaffolded app contains the gate
• Tests cover the hook decisions (block, allow, overrides, test-shrink)