chore(01-13): wave-0 — clean broken Approach-A artifacts per 01-11-SUMMARY

Restore a clean baseline before promoting the c647f61 prototype to
production paths (Wave 1) and building out Approach-B driver
scaffolding (Wave 2). All deletions trace back to falsifications
documented in 01-11-SUMMARY.md.

Deleted — broken Approach-A files:
  - src/test-hooks/sw-hooks.ts
      MV3 SW blocks dynamic import (Chromium es_modules.md;
      w3c/webextensions#212). The gated `await import('../test-hooks/
      sw-hooks')` from 01-11 Wave 1 never resolved → SW silently died →
      production listeners never registered. File was dead-on-arrival;
      no fix possible while MV3 SWs disallow dynamic import. Approach-B
      replaces SW-side instrumentation with the extension-internal
      harness page's chrome.action.* + chrome.notifications.* surface
      (full privilege; no monkey-patching needed).

  - tests/uat/lib/{launch,extension,sw,offscreen,assertions}.ts
      Popup-bridge architecture (01-11 dbd977c) — falsification 2 +
      falsification 3 in 01-11-SUMMARY: `sw.evaluate` exposes only
      chrome.{loadTimes,csi}, NOT chrome.action.* / chrome.notifications.*
      / chrome.runtime.sendMessage; setPopup-juggling for extension-id
      resolution turned out to be unnecessary (browser.extensions()
      works directly per the prototype). These files will be reborn in
      Wave 2 around the extension-page architecture.

      Kept: tests/uat/lib/zip.ts (host-side JSZip work — architecture-
      agnostic; A12+A13 still use it) and tests/uat/lib/test-hook-
      contract.d.ts (type mirror — extended in Wave 3 but kept as-is here).

  - tests/uat/prototype/probe_{offscreen,sw,tabs,tabs2}.mjs
      Feasibility-research probes (01-11 spike) that empirically falsified
      the Approach-A hypotheses. The findings are encoded in 01-11-
      SUMMARY.md; the probes themselves are dead code.

  - tests/uat/harness.test.ts
      01-11 Wave 2 popup-bridge orchestrator (dbd977c). Imports the
      now-deleted tests/uat/lib/{assertions,extension,sw,offscreen,launch}
      modules — would not typecheck after this commit. Reborn in
      Wave 3A as the Approach-B orchestrator (extension-internal page
      driver + A0 grep gate + 13 assertion drivers).

Reverted — SW-side dynamic-import gate comment block:
  - src/background/index.ts lines 13-29
      The existing comment block (post-spike) described the SW-side
      gated dynamic import that never landed. Rewritten to cite 01-13
      Approach-B explicitly, link to 01-11-SUMMARY.md falsification,
      and clarify that the Tier-1 grep gate's enduring value is
      catching regressions in the offscreen chunk's __MOKOSH_UAT__
      gate (the SW chunk is hook-free by construction).

Updated — Tier-1 grep gate FORBIDDEN_HOOK_STRINGS inventory:
  - tests/background/no-test-hooks-in-prod-bundle.test.ts
      Removed: `simulateUserStop` (Approach-A naming; replaced by
      Approach-B `dispatchEndedOnTrack` which matches the W3C
      dispatchEvent semantics per RESEARCH §7 BLOCKER — track.stop()
      does NOT fire 'ended' per spec, so the simulation MUST use
      dispatchEvent).
      Added: `installFakeDisplayMedia`, `uninstallFakeDisplayMedia`,
      `dispatchEndedOnTrack`, `__mokoshOffscreenQuery`.
      Total inventory: 8 surface strings (was 5). Each MUST be absent
      from every file under dist/ post-build.

Verification (all GREEN):
  - `npm run build` — exit 0; dist/ populated.
  - `grep -rln <forbidden> dist/` — 0 matches.
  - `npm run build:test` — exit 0; dist-test/ populated; offscreen-hooks
    chunk contains `installFakeDisplayMedia` (gate runs correctly
    against the test build's distinct artifact).
  - `npx tsc --noEmit` — exit 0 (root + tests/uat/tsconfig.json).
  - `npx vitest run` — 92/92 tests passing (was 89; the +3 new tests
    come from the FORBIDDEN_HOOK_STRINGS list expanding 5 → 8 — each
    forbidden string is one parametric `it(...)` block).

Both prior-failing tests now GREEN:
  - tests/background/sw-bundle-import.test.ts (was missing dist/ → 92/92
    requires the test run to have a current dist/; vitest gate test
    rebuilds via execFile when SKIP_BUILD≠1, otherwise relies on prior
    `npm run build`).
  - tests/background/no-test-hooks-in-prod-bundle.test.ts (was failing
    on stale dist; now GREEN against the freshly-rebuilt clean bundle).

Wave 1 (next): promote tests/uat/prototype/{extension-page-harness.html,
extension-page-harness.ts,a6.test.ts} to tests/uat/ via `git mv`;
update vite.test.config.ts rollup input.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

tests/background/no-test-hooks-in-prod-bundle.test.ts

@@ -42,12 +42,29 @@
 // bundle could carry leaked hooks unnoticed.
 //
 // Surface inventory enforced (each MUST be absent from any file under
-// dist/ once builds + future plans add to the hook tree):
-//   - `__mokoshTest`              — the global surface name itself
-//   - `simulateUserStop`          — Bug B simulate function (Plan 01-11 §3)
-//   - `getSegmentCount`           — Plan 01-11 Task 7 segments-count getter
-//   - `setCurrentStream`          — Plan 01-11 Task 2 offscreen wire
-//   - `setSegmentCountGetter`     — Plan 01-11 Task 7 offscreen wire
+// dist/). Plan 01-13 Wave 0 updated this list for the Approach-B
+// architecture (extension-internal harness page + offscreen-side
+// synthetic stream + chrome.runtime.sendMessage bridge), replacing the
+// 01-11 Approach-A SW-side instrumentation surface. The 01-11 entries
+// `simulateUserStop` (renamed to `dispatchEndedOnTrack` to match the
+// W3C dispatchEvent semantics per RESEARCH §7 BLOCKER) is dropped.
+//
+//   - `__mokoshTest`                — the global surface name itself
+//   - `setCurrentStream`            — Plan 01-11 Task 2 offscreen wire (retained)
+//   - `setSegmentCountGetter`       — Plan 01-11 Task 7 offscreen wire (retained)
+//   - `installFakeDisplayMedia`     — 01-13 synthetic getDisplayMedia install
+//   - `uninstallFakeDisplayMedia`   — 01-13 synthetic getDisplayMedia teardown
+//   - `dispatchEndedOnTrack`        — 01-13 Bug B simulate via dispatchEvent
+//                                     (replaces Approach-A `simulateUserStop`)
+//   - `getSegmentCount`             — Plan 01-11 Task 7 segments-count getter (retained)
+//   - `__mokoshOffscreenQuery`      — 01-13 page→offscreen bridge message type
+//
+// Total: 8 surface strings. Each MUST be absent from EVERY file under
+// `dist/` post-build. The list is mirrored by the harness's A0
+// assertion (tests/uat/harness.test.ts in Wave 3A) so the same
+// invariant is enforced at unit-test time (fast, every CI run) AND
+// at UAT-harness time (belt+suspenders per the orchestrator-loaded
+// `feedback-pre-checkpoint-bundle-gates.md` memory).
 //
 // Implementation mirrors `sw-bundle-import.test.ts`'s execFile pattern:
 //   - Spawn `npm run build` via execFile so the build is reproducible
@@ -85,10 +102,13 @@ const execFileAsync = promisify(execFile);
  */
 const FORBIDDEN_HOOK_STRINGS: ReadonlyArray<string> = [
   '__mokoshTest',
-  'simulateUserStop',
-  'getSegmentCount',
   'setCurrentStream',
   'setSegmentCountGetter',
+  'installFakeDisplayMedia',
+  'uninstallFakeDisplayMedia',
+  'dispatchEndedOnTrack',
+  'getSegmentCount',
+  '__mokoshOffscreenQuery',
 ];
 
 /** How long the build child has to finish (`npm run build` is ~10s).