Fix warnings, update deps, Metro-style task detail, comment counts

Warnings fixed:
- Removed unused imports (FieldMask, UpdateMemoRequest, LocalUriHandler,
  LocalPlatformContext, Composable in Color.kt)
- Removed unused Android color resources (old Material purple/teal)
- Replaced proguard-rules.pro with clean Compose/KMP config
- Fixed RelationDto to match actual API (memo/relatedMemo are objects)

Dependencies bumped:
- Ktor 3.4.3 → 3.5.0, Activity Compose 1.10.1 → 1.13.0
- Core KTX 1.16.0 → 1.18.0, SQLite 2.5.1 → 2.6.2
- WorkManager 2.11.1 → 2.11.2, JUnit 1.1.5 → 1.3.0, Espresso 3.5.1 → 3.7.0

Features:
- TaskDetailSheet converted to Metro AlertDialog style (no Material chips)
- MemoDetailScreen: edit button, created/updated timestamps at top
- Comment count shown on MemoCard header (computed from COMMENT relations)
- Explorer tag table: combined columns for memo count + task count per tag

Co-Authored-By: Claude Opus 4.6 (1M context)

Signed-off-by: Avinal Kumar <avinal.xlvii@gmail.com>

gradle/libs.versions.toml

@@ -5,14 +5,14 @@ compose-multiplatform = "1.11.0"
 ksp = "2.3.7"
 
 # AndroidX
-core-ktx = "1.16.0"
-activity-compose = "1.10.1"
+core-ktx = "1.18.0"
+activity-compose = "1.13.0"
 lifecycle = "2.10.0"
 navigation = "2.9.2"
 datastore = "1.2.1"
-work = "2.11.1"
+work = "2.11.2"
 room = "2.8.4"
-sqlite = "2.5.1"
+sqlite = "2.6.2"
 
 # Kotlin Multiplatform
 kotlinx-coroutines = "1.11.0"
@@ -20,15 +20,15 @@ kotlinx-datetime = "0.8.0"
 kotlinx-serialization = "1.11.0"
 
 # Networking
-ktor = "3.4.3"
+ktor = "3.5.0"
 
 # Image loading
 coil = "3.4.0"
 
 # Testing
 junit = "4.13.2"
-junit-android = "1.1.5"
-espresso = "3.5.1"
+junit-android = "1.3.0"
+espresso = "3.7.0"
 
 [libraries]
 # AndroidX