ui: improve Compose stability and message UI

- Add minute/second abbreviations and kotlin.time-based relative time formatter
- Introduce FastPreview and update previews to use AppTheme with dark/dynamic colors
- Refactor attachments preview grid & waveform to use ImmutableList and reduce recompositions
- Tweak message bubble reply styling and swipe-to-reply animation/haptics
- Add Compose Stability Analyzer plugin and enable it in debug builds
- Cache shared images by sha256 and improve share intent/chooser text
- Minor UX polish (e.g., “No views”) and immutability annotations

feature/convos/src/main/kotlin/dev/meloda/fast/convos/presentation/ConvosScreen.kt

@@ -53,6 +53,7 @@ import androidx.compose.ui.unit.DpOffset
 import androidx.compose.ui.unit.IntOffset
 import androidx.compose.ui.unit.LayoutDirection
 import androidx.compose.ui.unit.dp
+import com.skydoves.compose.stability.runtime.TraceRecomposition
 import dev.chrisbanes.haze.hazeEffect
 import dev.chrisbanes.haze.hazeSource
 import dev.chrisbanes.haze.materials.ExperimentalHazeMaterialsApi