Enhance PhotoViewer with share and open-in actions, improve reply UI

This commit introduces "Share" and "Open in..." actions to the `PhotoViewScreen`, allowing users to share images via other apps or open them in external viewers.

**Key changes:**

- **PhotoViewer:**
    - Added "Share" and "Open in..." options to the `PhotoViewScreen` dropdown menu.
    - `PhotoViewViewModel`:
        - Implemented `onShareClicked()` and `onOpenInClicked()` to handle these new actions.
        - Added `shareRequest` StateFlow to manage image sharing intents.
        - Introduced `downloadAndStoreImageToCache()` to download and cache images for sharing.
        - `onImageShared()` resets `shareRequest` after sharing.
    - Updated `TopBar` to include the new menu items.
    - Added string resources for "Open in…" and "Share".
- **Reply UI:**
    - `Reply.kt`: Title and summary text now use `TextOverflow.Ellipsis` to prevent long text from breaking the layout.
- **API Model:**
    - `MessagesResponse.kt`: Added `MessagesMarkAsImportantResponse` data class to handle the response for marking messages as important.
- **Data Layer:**
    - `MessagesRepositoryImpl`: Updated `markAsImportant` to correctly map the API response using `MessagesMarkAsImportantResponse`.
- **Minor:**
    - `README.md`: Updated feature checklist for external viewer.
    - `ApplicationModule.kt`: Added experimental Coil API opt-in.

feature/messageshistory/src/main/kotlin/dev/meloda/fast/messageshistory/presentation/attachments/Reply.kt

@@ -21,6 +21,7 @@ import androidx.compose.ui.Modifier
 import androidx.compose.ui.draw.clip
 import androidx.compose.ui.graphics.Color
 import androidx.compose.ui.graphics.Shape
+import androidx.compose.ui.text.style.TextOverflow
 import androidx.compose.ui.tooling.preview.Preview
 import androidx.compose.ui.unit.Dp
 import androidx.compose.ui.unit.dp
@@ -50,7 +51,6 @@ fun Reply(
                 bottom = bottomPadding
             )
     ) {
-
         Row(
             modifier = Modifier
                 .clip(RoundedCornerShape(12.dp))
@@ -74,14 +74,16 @@ fun Reply(
                 Text(
                     text = title,
                     style = MaterialTheme.typography.labelMedium,
-                    maxLines = 1
+                    maxLines = 1,
+                    overflow = TextOverflow.Ellipsis
                 )
 
                 summary?.let {
                     Text(
                         text = summary,
                         style = MaterialTheme.typography.labelSmall,
-                        maxLines = 1
+                        maxLines = 1,
+                        overflow = TextOverflow.Ellipsis
                     )
                 }
             }