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>

pubspec.lock

@@ -1,6 +1,14 @@
 # Generated by pub
 # See https://dart.dev/tools/pub/glossary#lockfile
 packages:
+  archive:
+    dependency: transitive
+    description:
+      name: archive
+      sha256: a96e8b390886ee8abb49b7bd3ac8df6f451c621619f52a26e815fdcf568959ff
+      url: "https://pub.dev"
+    source: hosted
+    version: "4.0.9"
   args:
     dependency: transitive
     description:
@@ -33,6 +41,22 @@ packages:
       url: "https://pub.dev"
     source: hosted
     version: "1.4.1"
+  checked_yaml:
+    dependency: transitive
+    description:
+      name: checked_yaml
+      sha256: "959525d3162f249993882720d52b7e0c833978df229be20702b33d48d91de70f"
+      url: "https://pub.dev"
+    source: hosted
+    version: "2.0.4"
+  cli_util:
+    dependency: transitive
+    description:
+      name: cli_util
+      sha256: ff6785f7e9e3c38ac98b2fb035701789de90154024a75b6cb926445e83197d1c
+      url: "https://pub.dev"
+    source: hosted
+    version: "0.4.2"
   clock:
     dependency: transitive
     description:
@@ -198,6 +222,14 @@ packages:
       url: "https://pub.dev"
     source: hosted
     version: "0.6.0"
+  flutter_launcher_icons:
+    dependency: "direct dev"
+    description:
+      name: flutter_launcher_icons
+      sha256: "10f13781741a2e3972126fae08393d3c4e01fa4cd7473326b94b72cf594195e7"
+      url: "https://pub.dev"
+    source: hosted
+    version: "0.14.4"
   flutter_lints:
     dependency: "direct dev"
     description:
@@ -264,6 +296,22 @@ packages:
       url: "https://pub.dev"
     source: hosted
     version: "4.1.2"
+  image:
+    dependency: transitive
+    description:
+      name: image
+      sha256: f9881ff4998044947ec38d098bc7c8316ae1186fa786eddffdb867b9bc94dfce
+      url: "https://pub.dev"
+    source: hosted
+    version: "4.8.0"
+  json_annotation:
+    dependency: transitive
+    description:
+      name: json_annotation
+      sha256: cb09e7dac6210041fad964ed7fbee004f14258b4eca4040f72d1234062ace4c8
+      url: "https://pub.dev"
+    source: hosted
+    version: "4.11.0"
   leak_tracker:
     dependency: transitive
     description:
@@ -416,6 +464,14 @@ packages:
       url: "https://pub.dev"
     source: hosted
     version: "2.3.0"
+  petitparser:
+    dependency: transitive
+    description:
+      name: petitparser
+      sha256: "91bd59303e9f769f108f8df05e371341b15d59e995e6806aefab827b58336675"
+      url: "https://pub.dev"
+    source: hosted
+    version: "7.0.2"
   platform:
     dependency: transitive
     description:
@@ -432,6 +488,14 @@ packages:
       url: "https://pub.dev"
     source: hosted
     version: "2.1.8"
+  posix:
+    dependency: transitive
+    description:
+      name: posix
+      sha256: "185ef7606574f789b40f289c233efa52e96dead518aed988e040a10737febb07"
+      url: "https://pub.dev"
+    source: hosted
+    version: "6.5.0"
   pub_semver:
     dependency: transitive
     description:
@@ -613,6 +677,14 @@ packages:
       url: "https://pub.dev"
     source: hosted
     version: "1.1.0"
+  xml:
+    dependency: transitive
+    description:
+      name: xml
+      sha256: "971043b3a0d3da28727e40ed3e0b5d18b742fa5a68665cca88e74b7876d5e025"
+      url: "https://pub.dev"
+    source: hosted
+    version: "6.6.1"
   yaml:
     dependency: transitive
     description: