Straw phase H: Settings screen + SponsorBlock category toggles

New: SettingsStore (SharedPreferences-lite, same pattern as HistoryStore)
exposes a Set<SbCategory> StateFlow.

7 SponsorBlock categories surfaced as toggle rows in a new Settings screen:
sponsor (on by default), selfpromo, intro, outro, interaction (reminders),
music_offtopic (talking in music videos), filler.

Wiring:
- StrawApp.onCreate: Settings.init(this)
- StrawHome: new Settings gear icon next to "straw v0.1.0" header. Tap
  routes to Screen.Settings.
- PlayerViewModel.resolve: reads Settings.get().sbCategories on resolve.
  Empty set = SponsorBlock skip disabled (no API call).

Material-icons-core dep added (1.7.5) for the Icons.Filled.Settings glyph.

Day-4 ideas: theme override, default audio-only playback, preferred quality,
clear history buttons.

strawApp/build.gradle.kts

@@ -81,6 +81,7 @@ dependencies {
     implementation(libs.jetbrains.compose.foundation)
     implementation(libs.jetbrains.compose.material3)
     implementation(libs.jetbrains.compose.ui)
+    implementation("androidx.compose.material:material-icons-core:1.7.5")
 
     // Lifecycle + ViewModel for Compose
     implementation("androidx.lifecycle:lifecycle-viewmodel-compose:2.10.0")