fix(settings): don't crash on load when localStorage is blocked + tests (+6)

Prevention work found a real bug: getSettings() runs at module load, and its
catch block called localStorage.removeItem() — but we often reach that catch
*because* localStorage access threw (blocked storage / private mode / sandboxed
context). The removeItem then re-threw, producing an uncaught error that crashed
the whole app at startup. Guarded the cleanup in its own try/catch.

New state/settings suite (6) covers the legacy-boolean callNoiseSuppression
migration, denoise-model/ringtone-id coercion of unknown values, default merge,
malformed JSON, and the blocked-storage regression.

Full suite now 129 tests, all passing.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

src/app/state/settings.ts

@@ -296,7 +296,15 @@ export const getSettings = (): Settings => {
       },
     };
   } catch {
-    localStorage.removeItem(STORAGE_KEY);
+    // We may be here precisely because localStorage access throws (blocked
+    // storage / private mode / sandboxed context). Removing the key must not be
+    // allowed to re-throw — getSettings() runs at module load, so an uncaught
+    // error here would crash the whole app on startup.
+    try {
+      localStorage.removeItem(STORAGE_KEY);
+    } catch {
+      /* localStorage unavailable — nothing to clean up */
+    }
     return defaultSettings;
   }
 };