feat: fix sync counters, polished activity rows, Files tab, new icon

- Fix SYNC_COMPLETED showing ↑0 ↓0 ✗0 when only deletions occurred: add ✕N
  for deleted files to the summary message (↑N ↓N ✕N ✗N format)
- Fix PairDetail Activity section showing raw "SYNC_STARTED" enum names and
  "remote" as a plain subtitle: replace dot-based EventRow with the same
  polished icon-bubble rows as the global Log tab
- Extract shared SyncEventRow composable + iconAndTint/label helpers to
  ui/shared/SyncEventRow.kt; both LogScreen and PairDetailScreen now use it
- Add Files tab (4th tab between Log and Accounts): folder browser showing
  all synced files per pair, grouped by subdirectory, with file-type icons,
  size, last-synced date, and a summary header (N files, total size)
- Add SyncFileStateDao.observeForPair() reactive Flow query for Files tab
- Completely redesign app icon: near-black radial gradient background with
  three bold directional arrows in an S-pattern (coral → silver → teal),
  each with gradient fills and tip-glow dots — entirely different from the
  typical circular sync-arrow style
- Bump version to 1.0.22 (build 23)

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

app/src/main/res/drawable/ic_launcher_background.xml

@@ -1,9 +1,11 @@
 <?xml version="1.0" encoding="utf-8"?>
 <shape xmlns:android="http://schemas.android.com/apk/res/android">
     <gradient
-        android:type="linear"
-        android:angle="135"
-        android:startColor="#2E1065"
-        android:centerColor="#6D28D9"
-        android:endColor="#1E40AF"/>
+        android:type="radial"
+        android:gradientRadius="80%"
+        android:centerX="0.35"
+        android:centerY="0.3"
+        android:startColor="#1C1124"
+        android:centerColor="#0E0A18"
+        android:endColor="#060408"/>
 </shape>