feat(installer): remove-USB-stick hint on the reboot screen

Adds a bold "Remove the USB stick now" line before the reboot, plus a
muted fallback paragraph pointing at the BIOS one-time boot menu keys
(F11/F12/Esc) for when removal isn't enough. Caught on the 2026-04-21
Medion bare-metal test: the box didn't boot the installed system on
first reboot and required manual BIOS boot-order changes, which
non-technical users won't know how to do.

Template-only change. No new CSS, no new code paths — <kbd> uses
browser defaults, <strong> keeps the hierarchy readable.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

CHANGELOG.md

@@ -9,6 +9,13 @@ This project uses calendar versioning: `YY.N-stage` (e.g. `26.0-alpha` = 2026, r
 
 ### Added
 
+- **Remove-USB-stick hint on the installer's post-install screen.**
+  `webinstaller/templates/install/rebooting.html` now shows a bold
+  "Remove the USB stick now" line before the reboot, plus a muted
+  fallback explaining the BIOS boot-menu keys (F11/F12/Esc) if the
+  machine boots back into the installer anyway. Caught on the first
+  bare-metal test (Medion i5-4gen, 2026-04-21) where the box didn't
+  boot the installed system without manual BIOS-order changes.
 - **New `path` setting type for app manifests.** Apps can now declare a
   setting with `"type": "path"` whose value is an absolute filesystem
   path on the host; docker-compose bind-mounts it via the usual `.env`

webinstaller/templates/install/rebooting.html

@@ -6,6 +6,8 @@
 {% block content %}
 <h1>Rebooting…</h1>
 <p class="lede">The machine is restarting. This page will stop responding in a moment — that's expected.</p>
+<p><strong>Remove the USB stick now</strong> — if it's still plugged in when the machine reboots, some BIOS setups will boot into this installer again instead of starting Furtka.</p>
+<p class="muted">If the installer does come back anyway, your BIOS is set to boot from USB before the disk. Press the one-time boot menu key at startup (often <kbd>F11</kbd>, <kbd>F12</kbd>, or <kbd>Esc</kbd> — it flashes briefly on screen) and pick the internal disk, or change the boot order in BIOS settings.</p>
 <p>When the machine comes back up (~1 minute), open Furtka in your browser:</p>
 <p><a href="http://{{ hostname }}.local" class="btn btn-primary">http://{{ hostname }}.local</a></p>
 <p class="muted">If that doesn't resolve, your network may not support mDNS — use the IP address shown on the machine's console instead.</p>