Refactoring to facet support reverted that change. Bring it back, with pain.

Replace `CircularProgressIndicator` with the new `CircularWavyProgressIndicator` from Material 3 Expressive when a post is being uploaded.

This change provides a more modern-looking progress indicator. The `@OptIn` for `ExperimentalMaterial3ExpressiveApi` has been added to support this.

Simplify the logic for filtering replies in a thread. The new implementation makes it easier to follow the conditions under which a reply is shown.

- If a user follows the parent and the root of a three-post thread, the reply is shown.
- For threads with four or more posts, the reply is shown if the user follows the parent, root, and grandparent.
- Add `parentsParentRef()` and `grandparentAuthor()` helper functions to traverse the reply chain.

Add "Replied to you" and "Mentioned you" labels to the corresponding notification types. This is achieved by passing new boolean flags, `renderingReplyNotif` and `renderingMention`, from the `NotificationsView` to the `SkeetView`.

Delete unused commented-out code and a redundant variable assignment related to embedded media.

Remove the redundant conditional check within the post button's `onClick` lambda. The button's `enabled` state already handles the validation for post text length and content, making the inner `if` statement unnecessary.

Enable the Gradle configuration cache to improve build performance by caching the result of the configuration phase and reusing it for subsequent builds.