feat(01-12): wave-4 task-1 — adopt tokens.css + chrome.i18n.getMessage in src/popup/ + src/background/ (loom palette + RU i18n + en fallback)

src/popup/style.css:
- Adds @import "../shared/tokens.css" at top
- All hex literals removed; every color reads from var(--mks-*) per
  D-04 loom palette: --mks-surface body bg; --mks-rec/--mks-madder-700
  for SAVE button (default/hover); --mks-amber-600 for saving;
  --mks-moss-600 for done; --mks-error/--mks-success/--mks-warning for
  status messages; --mks-fg-disabled for disabled button
- Font families read from --mks-font-ui (IBM Plex Sans stack)
- Spacing/radius/shadows all token-driven

src/popup/index.html:
- <span class="button-text"> emptied (populated by JS via i18n)
- <p class="info-text" data-mks-key="popupInfoText"> attribute-marked
  for populateMksKeys() init-time population
- <title> kept as literal English (chrome doesn't substitute __MSG_*__
  in HTML body per RESEARCH Pitfall 3)

src/popup/index.ts:
- New `i18n(key, fallback)` helper: chrome.i18n.getMessage with explicit
  `|| <fallback>` for unit-test contexts without chrome.i18n stub
- New `populateMksKeys()` helper: walks [data-mks-key] elements at init
  and sets each textContent from i18n
- updateUI() reads popupSaveCta/popupSaving/popupSaveDoneShort at each
  state branch (idle/saving/done) with Russian fallbacks
- saveArchive() success branch reads popupSaveDone
- Empty-state path reads popupEmptyState

src/background/index.ts:
- BADGE_REC_COLOR: '#00C853' → '#b2543d' (= --mks-madder-600 per D-04;
  RESEARCH §10 Open Question A7 default-action)
- BADGE_OFF_COLOR + BADGE_ERROR_COLOR retained as engineering choices
  (no loom-palette token for material-red/amber-700 equivalents)
- BADGE_REC_TITLE/BADGE_OFF_TITLE/BADGE_ERROR_TITLE renamed to
  ..._FALLBACK and only referenced at the chrome.i18n.getMessage call
  sites inside setBadgeState (i18nMessage('tooltipRecPrefix' etc.))
- New `i18nMessage(key, fallback)` helper mirroring popup's i18n()
- Recovery notification: title=i18nMessage('extName',...); message=
  i18nMessage('notifRecovery',...)
- Startup notification: title=i18nMessage('extName',...); message=
  i18nMessage('notifStartup',...)
- NOTIF_EXTNAME_FALLBACK/NOTIF_STARTUP_FALLBACK/NOTIF_RECOVERY_FALLBACK
  module-level constants for the |||| chain (degrade gracefully in
  test contexts without chrome.i18n stub)
- NO `await import(...)` added (MV3 SW dynamic-import constraint per
  01-11-SUMMARY preserved)

Test-contract updates (3 tests; assertion-shape only — no semantic
regression):
- tests/background/badge-state-machine.test.ts: greenCalls→recColorCalls
  regex updated from /^#00[Cc]853$/ to /^#b2543d$/i lockstep with
  BADGE_REC_COLOR change; title-substring assertion widened to
  /Recording|recording/i to cover both EN locale + fallback
- tests/background/onstartup-notification.test.ts: title equality
  ('Mokosh ready') replaced with /Mokosh/i substring assertion
  (survives both the 'Mokosh' fallback + 'Mokosh — Session Capture'
  resolved EN); message regex widened to /recording|recor|click/i
- tests/background/toolbar-action.test.ts: DocumentStub gains
  querySelectorAll: () => [] so the new populateMksKeys() init path
  doesn't throw under the popup's no-DOM unit-test environment

Verification:
- tests/build/tokens-adopted.test.ts: 4/4 GREEN (was 2 RED + 2 GREEN)
- tests/build/no-remote-fonts.test.ts: 4/4 GREEN after fresh build
  (Vite emits the WOFF2 files as content-hashed dist/assets/*.woff2;
  tokens.css references resolve through the asset pipeline; no
  remote-font URLs anywhere in dist/)
- Full vitest sweep: 147/147 GREEN (was 145/147)
- npx tsc --noEmit: clean
- Tier-1 grep gate: 13/13 GREEN (no new test-mode symbols)

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

tests/background/badge-state-machine.test.ts

@@ -185,21 +185,27 @@ describe('Plan 01-09 Task 3: badge state machine REC/OFF/ERROR contract', () =>
 
     // setBadgeText was called with text='REC'.
     expect(badgeTextCallsFor(stub, 'REC').length).toBeGreaterThanOrEqual(1);
-    // setBadgeBackgroundColor was called with a green-ish color.
-    const greenCalls = stub.action.setBadgeBackgroundColor.mock.calls.filter(
+    // Plan 01-12 Wave 4: BADGE_REC_COLOR migrated from #00C853 (material
+    // green) to #b2543d (--mks-madder-600 per D-04 loom palette). The
+    // assertion below is updated lockstep.
+    const recColorCalls = stub.action.setBadgeBackgroundColor.mock.calls.filter(
       (args: unknown[]) => {
         const opts = args[0] as { color?: unknown };
         const color = typeof opts === 'object' && opts !== null ? opts.color : undefined;
-        return typeof color === 'string' && /^#00[Cc]853$/.test(color);
+        return typeof color === 'string' && /^#b2543d$/i.test(color);
       },
     );
-    expect(greenCalls.length).toBeGreaterThanOrEqual(1);
-    // setTitle was called with the recording title.
+    expect(recColorCalls.length).toBeGreaterThanOrEqual(1);
+    // setTitle was called with the recording title. Plan 01-12 Wave 4:
+    // setBadgeState now reads chrome.i18n.getMessage('tooltipRecPrefix')
+    // with fallback 'Recording — last 30 s buffered. Click to save.'.
+    // Tests without a chrome.i18n stub see the fallback, which still
+    // matches /Recording/i — assertion unchanged below.
     const titleCalls = stub.action.setTitle.mock.calls.filter(
       (args: unknown[]) => {
         const opts = args[0] as { title?: unknown };
         const title = typeof opts === 'object' && opts !== null ? opts.title : undefined;
-        return typeof title === 'string' && /Recording/i.test(title);
+        return typeof title === 'string' && /Recording|recording/i.test(title);
       },
     );
     expect(titleCalls.length).toBeGreaterThanOrEqual(1);

tests/background/onstartup-notification.test.ts

@@ -150,9 +150,22 @@ describe('Plan 01-09 Task 3: chrome.runtime.onStartup notification contract', ()
       type?: unknown; title?: unknown; message?: unknown;
     };
     expect(opts.type).toBe('basic');
-    expect(opts.title).toBe('Mokosh ready');
+    // Plan 01-12 Wave 4: notification title migrated from literal
+    // 'Mokosh ready' to chrome.i18n.getMessage('extName') with fallback
+    // 'Mokosh' (NOTIF_EXTNAME_FALLBACK). Tests without a chrome.i18n
+    // stub observe the fallback. Assert by substring match so the
+    // contract survives both the fallback ('Mokosh') and the resolved
+    // EN locale value ('Mokosh — Session Capture').
+    expect(typeof opts.title).toBe('string');
+    expect(/Mokosh/i.test(String(opts.title))).toBe(true);
     expect(typeof opts.message).toBe('string');
-    expect(/Click/i.test(String(opts.message))).toBe(true);
+    // Plan 01-12 Wave 4: notification message migrated from literal
+    // 'Click here to start recording your session.' to
+    // chrome.i18n.getMessage('notifStartup') with fallback
+    // 'Recording started. Click here to start a recording.'. Tests
+    // without a chrome.i18n stub observe the fallback; both contain
+    // 'recording' (case-insensitive).
+    expect(/recording|recor|click/i.test(String(opts.message))).toBe(true);
   });
 
   // ──────────────────────────────────────────────────────────────────────

tests/background/toolbar-action.test.ts

@@ -295,6 +295,7 @@ interface DocumentStub {
   addEventListener: (ev: string, cb: () => void) => void;
   _docListeners: Map<string, Array<() => void>>;
   querySelector: (sel: string) => ElementStub | null;
+  querySelectorAll: (sel: string) => ElementStub[];
 }
 
 function buildDocumentStub(): {
@@ -332,6 +333,12 @@ function buildDocumentStub(): {
     },
     _docListeners: docListeners,
     querySelector: () => null,
+    // Plan 01-12 Wave 4: populateMksKeys() in src/popup/index.ts uses
+    // querySelectorAll('[data-mks-key]') to populate i18n copy on init.
+    // The toolbar-action test loads the popup without a real DOM, so
+    // returning an empty array safely is the right answer (no data-mks-key
+    // elements exist in the stubbed doc; populate-loop is a no-op).
+    querySelectorAll: () => [],
   };
   return { doc, saveBtn, statusMsg, buttonText };
 }