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.

site/README.md

@@ -27,9 +27,10 @@ handbook. Rebuild and refresh the browser after changing the site sources or gui
 
 ## GitHub Pages
 
-Choose **Settings → Pages → Source → GitHub Actions** to publish through the Pages
-workflow. It runs when site or documentation changes reach `main`; you can also
-start it manually. The expected address is https://ferese-wm.github.io/ferese/.
+Choose **Settings → Pages → Source → GitHub Actions** to enable publishing, then
+open **Actions → Deploy website to GitHub Pages → Run workflow** and choose the
+branch to publish. Deployment runs manually, and the expected address is
+https://ferese-wm.github.io/ferese/.
 
 The site uses relative links, including for handbook search, so it also works under the
 `/ferese/` project path. Each build copies screenshots from `docs/images` into