docs: restructure host setup by distro, configuration by compositor

Split the docs' single distro×desktop axis (ubuntu-gnome / ubuntu-kde / fedora-kde) into two,
which deduplicates the shared mechanics and scales to distros that run several desktops (Arch):

- Install the host — per distro/OS (ubuntu, fedora, arch, bazzite, steamos-host, windows-host):
  GPU driver + package + input group, then a canonical "Configure your desktop" funnel.
- Configure your desktop — per compositor (kde, gnome, gamescope, sway): host.env, compositor
  quirks, the headless session, and starting the host.

New shared web-console page (enable · login password · arm pairing) removes the console/password
block that was copy-pasted across all seven host pages. Merged ubuntu-gnome + ubuntu-kde into
ubuntu; renamed fedora-kde to fedora; kept bazzite and steamos-host as dedicated appliance guides
(trimmed of duplication). Moved the KWin headless session, the GNOME EGL/lock traps, and the
gamescope attach/managed model out of the distro pages onto their compositor pages.

Fixed while restructuring: distro-specific paths on kde (kde-desktop-setup.sh is Fedora/Bazzite-only;
the .deb ships host.env.kde under /usr/share/punktfunk-host), the interactive "start the host" step
that was lost in the merge, sway over-claiming Hyprland, and a pre-existing broken anchor in
how-it-works.

Removal of the three old pages was captured by the preceding commit 8ebb614 (a concurrent commit
swept up the staged git-rm); the net docs tree is correct. Fumadocs build + internal link/anchor
check green.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

docs-site/content/docs/windows-host.md

@@ -59,29 +59,24 @@ Packaging internals live in
 
 ### Web console & pairing
 
+See [The Web Console](/docs/web-console) for the console + pairing model shared with the Linux host;
+the Windows specifics follow.
+
 The installer also sets up the **web management console** (status, paired devices, the PIN pairing
 flow): it bundles the console plus its own runtime and runs it as the **`PunktfunkWeb`** task on
 **`http://<this-PC>:47992`**, starting at boot.
 
 #### Console login password
 
-During setup you choose the console **login password** — it's pre-filled with a secure random default
-and shown again on the installer's final page. It's stored in `%ProgramData%\punktfunk\web-password`
-(as `PUNKTFUNK_UI_PASSWORD=…`), readable only by Administrators and SYSTEM.
-
-To change it, edit that file and restart the console task. In an **elevated** PowerShell:
-
-```powershell
-notepad "$env:ProgramData\punktfunk\web-password"   # set PUNKTFUNK_UI_PASSWORD=<your-password>
-schtasks /End /TN PunktfunkWeb; schtasks /Run /TN PunktfunkWeb
-```
-
-Forgot it? This is the recovery path linked from the console login screen — see
+You choose the console **login password** during setup — a secure random default is pre-filled and
+shown on the installer's final page. It's stored in `%ProgramData%\punktfunk\web-password`, readable
+only by Administrators and SYSTEM. To read or change it (with the `schtasks` restart), see
+[The Web Console → Login password](/docs/web-console#login-password); forgot it entirely?
 [Forgot your Password?](/docs/forgot-password).
 
 The host **requires PIN pairing** by default (secure on a LAN). To connect the first time, open the
-console from any browser on the LAN, log in, go to **Devices → arm pairing**, and enter the PIN on
-your [client](/docs/clients). The host's own management API stays loopback-only behind the console.
+console from any browser on the LAN, log in, go to **Devices → [arm pairing](/docs/web-console#arm-pairing)**,
+and enter the PIN on your [client](/docs/clients). The host's own management API stays loopback-only behind the console.
 
 ### Configure