Add panel-wide styles and the Morph hub (#26)

Panel appearance now applies to the whole panel, with seven styles: Floating, Capsules, Notch, Edge to edge, Fused islands, Adaptive and Morph.

- Share composition, geometry, and motion through the renderer-independent `ferese-panel` crate, including native materials, input regions, and Settings previews.
- Add the Morph hub with media, calendar, notifications, controls, workspace previews, hover feedback, and attached mode. Keep recording and low-battery status visible and respect window clearance.
- Cache workspace preview geometry, draw thumbnails directly, centralize Morph transitions, and keep rendering settings local to each shell instance.
- Put Record Screen in the Morph header and show the display control only when an external monitor is connected. Update panel documentation, the desktop screenshot, and native check style names.

Local validation included 660 compositor tests, 191 shell tests, isolated preview-cache checks, GPU Morph captures at 1×/1.25×/1.5×, formatting, and Clippy with warnings denied. The final header change passed all 23 Morph tests. Release workflow jobs are skipped for this PR.

README.md

@@ -13,7 +13,7 @@
 
 Ferese combines a window manager and desktop shell with one configuration.
 
-![Ferese desktop with a translucent Now Playing popup showing Spotify artwork and playback controls](docs/images/screenshots/ferese-media.webp)
+![Ferese desktop with Morph's music view open over a sunset wallpaper](docs/images/screenshots/ferese-morph.webp)
 
 [View more screenshots](docs/screenshots.md)
 
@@ -21,7 +21,7 @@ Ferese combines a window manager and desktop shell with one configuration.
 
 - Scrolling columns, window groups, tree tiling and floating windows with saved size and position
 - Integrated shell with notifications, media controls, Settings and Control Center
-- [Custom panels](docs/configuration.md#panel-composition) with editable items, groups, surfaces, and top or bottom placement
+- [Custom panels](docs/panel-configuration.md) with seven styles, editable groups and items, and top or bottom placement
 - Workspace overview and recent-window switching
 - [Continuum animations](docs/configuration.md#animations): interruptible springs, gesture momentum and shared motion controls
 - Live wallpapers and blur, custom KDL themes, and Light/Dark/Auto modes
@@ -76,7 +76,8 @@ guide](docs/installation.md) also walks you through previews, updates and recove
 ## Configure
 
 Configure Ferese through **Control Center → Settings** or `~/.config/ferese/config.kdl`.
-Changes apply live. Invalid edits leave the last working configuration in place.
+Changes apply live, and if an edit is invalid, the last working configuration stays
+in place.
 
 The [configuration reference](docs/configuration.md) and [example
 config](packaging/config.kdl) cover appearance, window layouts,