Node-free swap: comp-fidelity verbs move to the engine

The four comp-fidelity scripts (comp-spec, comp-diff, font-match, build-phase)
and their six libs are ported into the impeccable-engine binary. This removes
the last Node .mjs from the skill: `git ls-files skill/scripts | grep '\.mjs$'`
now returns nothing.

- reference/new-work.md, reference/visualize.md, and the asset-producer /
  finish-reviewer agents now invoke `{{scripts_path}}/impeccable <verb>` instead
  of `node <script>.mjs`.
- Deleted the ten ported .mjs and the four JS unit tests that imported them
  (their behavior is now covered by the engine's Rust tests and the oracle);
  removed those files from scripts/test-suites.mjs.
- Added oracle cases (comp-*, font-match-*, build-phase-*) over a comp-basic
  workspace, recorded from the engine binary; the deterministic outputs are
  byte-identical to the JS the scripts left behind.
- docs/CLI-CONTRACT.md documents the four verbs, the CDP font rendering, and
  the runtime-resolved (never-committed) font-index catalog.

The font-index catalog JSON stays shipped in the skill (data/font-index.json);
the engine resolves it at run time and never vendors it.

Prepared with AI assistance (Claude Code).

scripts/test-suites.mjs

@@ -51,17 +51,13 @@ export const SUITES = {
         // A finite per-test cap so an async hang is cancelled and reported
         // rather than left running with `--test-timeout` unset (Infinity).
         // Note: this timer lives in the event loop, so it cannot interrupt a
-        // test blocked in a synchronous spawnSync; the child bounds in
-        // tests/build-phase.test.mjs and the runner's wall-clock group-kill
-        // cover that case. The slowest core test is ~11s, so 180s is safe.
+        // test blocked in a synchronous spawnSync; the runner's wall-clock
+        // group-kill covers that case. The slowest core test is ~11s, so 180s
+        // is safe.
         timeoutMs: 180000,
         files: [
-          'tests/build-phase.test.mjs',
           'tests/ci-test-plan.test.mjs',
-          'tests/comp-diff.test.mjs',
-          'tests/font-match.test.mjs',
           'tests/github-sheriff.test.mjs',
-          'tests/hero-checks.test.mjs',
           'tests/hook-build.test.mjs',
           'tests/openai-plugin.test.mjs',
           'tests/release.test.mjs',