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>

gradle/libs.versions.toml

@@ -10,6 +10,7 @@ androidx-espresso = "3.7.0"
 androidx-lifecycle = "2.9.5"
 androidx-navigation = "2.9.1"
 androidx-testExt = "1.3.0"
+coil = "3.0.4"
 composeHotReload = "1.0.0-rc02"
 composeMultiplatform = "1.9.1"
 junit = "4.13.2"
@@ -44,6 +45,8 @@ ktor-client-cio = { module = "io.ktor:ktor-client-cio", version.ref = "ktor" }
 ktor-client-js = { module = "io.ktor:ktor-client-js", version.ref = "ktor" }
 kotlinx-coroutines-core = { module = "org.jetbrains.kotlinx:kotlinx-coroutines-core", version.ref = "kotlinx-coroutines" }
 kotlinx-coroutines-android = { module = "org.jetbrains.kotlinx:kotlinx-coroutines-android", version.ref = "kotlinx-coroutines" }
+coil-compose = { module = "io.coil-kt.coil3:coil-compose", version.ref = "coil" }
+coil-network-ktor3 = { module = "io.coil-kt.coil3:coil-network-ktor3", version.ref = "coil" }
 
 [plugins]
 androidApplication = { id = "com.android.application", version.ref = "agp" }