Add search, offline queue, app icon, and UI polish

- Collapsible search in notes and tasks: magnifying glass in AppBar
  expands to a text field inline; close button resets the filter
- Offline capture queue: failed quick-captures (NetworkException) are
  persisted to SharedPreferences and retried automatically on next
  successful submit or app start; badge shows pending count
- App icon: book-with-sparkle logo from FabledAssistant SVG rendered
  at all Android densities with adaptive icon (indigo #6366f1 bg)
- Dark mode subtitle fix: use colorScheme.onSurfaceVariant for note
  preview and conversation timestamp text
- Remove swipe-to-delete (accidental deletions); long-press remains
- Chat: SSE streaming reliability, polling fallback, title patching
- Settings: theme toggle (system/light/dark) persisted to prefs
- Notes: delete button in edit screen; body preview in list
- Tasks: fix delete dialog context; description search support

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

android/app/src/main/res/mipmap-anydpi-v26/ic_launcher.xml

@@ -0,0 +1,9 @@
+<?xml version="1.0" encoding="utf-8"?>
+<adaptive-icon xmlns:android="http://schemas.android.com/apk/res/android">
+  <background android:drawable="@color/ic_launcher_background"/>
+  <foreground>
+      <inset
+          android:drawable="@drawable/ic_launcher_foreground"
+          android:inset="16%" />
+  </foreground>
+</adaptive-icon>

android/app/src/main/res/values/colors.xml

@@ -0,0 +1,4 @@
+<?xml version="1.0" encoding="utf-8"?>
+<resources>
+    <color name="ic_launcher_background">#6366f1</color>
+</resources>