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/installation.md

@@ -61,22 +61,23 @@ libraries.
 
 To run X11-only applications, Ferese launches
 [xwayland-satellite](https://github.com/Supreeeme/xwayland-satellite),
-which in turn needs an `Xwayland` binary. Both are runtime dependencies, not
-build dependencies, and neither is needed to build Ferese.
+which in turn needs an `Xwayland` binary. Both are runtime dependencies, so
+neither is needed to build Ferese.
 
 - `Xwayland` ships with the X.Org server packages: `xorg-x11-server-Xwayland`
   on Fedora and Debian/Ubuntu, `xorg-xwayland` on Arch.
 - `xwayland-satellite` is not packaged by most distributions. Build or install
   it from its upstream releases **with its `systemd` feature enabled**
-  (`cargo build --release --features systemd`). That feature is what sends the
-  `READY=1` readiness notification Ferese waits for. Upstream's default feature
-  set is empty, so a default build never sends it, Ferese's fixed 10-second
-  startup budget expires, and the service reports a startup failure instead of
-  a display. A spawned process that is still alive is not readiness.
+  (`cargo build --release --features systemd`), which sends the `READY=1`
+  notification Ferese waits for. Upstream's default feature set is empty, so a
+  default build never sends that notification: even if the process remains alive,
+  Ferese's fixed 10-second startup budget expires and the service reports a
+  startup failure instead of a display.
 
 Both the compositor's default and the packaged configuration ship with X11
 enabled, so a session with the two pieces above needs no configuration change.
-If you maintain your own `config.kdl`, the block to keep is
+If you maintain your own `config.kdl`, keep this block in
+`~/.config/ferese/config.kdl`:
 
 ```kdl
 xwayland {
@@ -86,8 +87,7 @@ xwayland {
 }
 ```
 
-in `~/.config/ferese/config.kdl` and starting a new session, then check
-`feresectl xwayland status`. See
+Start a new session, then check `feresectl xwayland status`. See
 [X11 support](configuration.md#x11-support-xwayland-satellite) for the full key
 list, diagnostics, and known limitations.