Add photo viewer for task completions on iOS and Android

- Add PhotoViewerDialog (Android) and PhotoViewerSheet (iOS) for viewing completion photos
- Add CompletionCardView (iOS) to display completion details with photo button
- Update AllTasksView (iOS) to show full completion details instead of just count
- Update TaskCard (Android) to use CompletionCard component
- Add Coil 3.0.4 image loading library for Android
- Configure ImageLoader in MainActivity with network, memory, and disk caching
- Add getMediaBaseUrl() to ApiClient for loading media files without /api path
- Fix photo viewer background color to match app theme

🤖 Generated with [Claude Code](https://claude.com/claude-code)

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

composeApp/build.gradle.kts

@@ -82,6 +82,8 @@ kotlin {
             implementation(libs.ktor.client.logging)
             implementation(compose.materialIconsExtended)
             implementation("org.jetbrains.kotlinx:kotlinx-datetime:<latest-version>")
+            implementation(libs.coil.compose)
+            implementation(libs.coil.network.ktor3)
         }
         commonTest.dependencies {
             implementation(libs.kotlin.test)