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.

docs/screen-sharing.md

@@ -1,12 +1,12 @@
 # Screen sharing and recording
 
 Share a monitor or window from a Wayland-compatible recording or conferencing app,
-or save a video using the top bar. [Installation](installation.md) includes the
-portal and PipeWire dependencies.
+or save a video using the panel's Recording control. The
+[installation guide](installation.md) covers the portal and PipeWire dependencies.
 
-## Record from the top bar
+## Record from the panel
 
-1. Click the recording icon.
+1. Click the Recording item in the panel, or open Controls → Recording in Morph.
 2. Choose a display and an audio source: **Off**, **System sound**, **Microphone**,
    or **Both**. Audio is off by default; the other choices use
    your default output or input device from audio settings.
@@ -38,9 +38,9 @@ The picker follows your shell colors, font, corners, opacity, and blur.
 ## Stop sharing
 
 Click **Stop sharing** or close the sharing window. For the built-in recorder,
-use the stop button in the top bar. Sharing also ends when the app closes or
-Ferese locks. If you disconnect a shared monitor or change its capture size,
-its stream ends and you need to start sharing again.
+use the panel's stop button, which Morph also shows while recording. Sharing
+also ends when the app closes or Ferese locks. If you disconnect a shared monitor
+or change its capture size, its stream ends and you need to start sharing again.
 
 ## Remember permissions