fix: move Chromium download to Docker build phase

- Download Chromium from Google snapshots during Docker build (network works there)
- Chroot hook now only verifies and installs runtime dependencies
- Remove generated files from repo (OVMF_VARS.fd, qemu.pid, screenshots)
- Update isotest scripts to use .nogit/ directory structure
- Chromium kiosk verified working with Sway compositor

readme.plan.md

@@ -4,10 +4,25 @@
 
 Custom Ubuntu 24.04 LTS ISO that boots into a kiosk mode with:
 - **Sway** (Wayland compositor) - managed by the daemon
-- **Google Chrome** in kiosk mode - managed by the daemon
+- **Chromium Browser** in kiosk mode - managed by the daemon
 - **eco-daemon** - Deno binary that orchestrates everything
 - **Management UI** on port 3006
 
+## REQUIREMENT: Sway + Chromium Browser
+
+**The system MUST use Chromium browser, NOT Google Chrome.**
+
+### Challenge
+Ubuntu 24.04 made `chromium-browser` snap-only. Snap doesn't work in live-build chroot environments.
+
+### Solution
+Download Chromium directly from official builds or use Debian's chromium package:
+- Option A: Download from https://download-chromium.appspot.com/ (Linux_x64)
+- Option B: Use Debian's chromium .deb package from sid/unstable
+- Option C: Use ungoogled-chromium from OBS (OpenSUSE Build Service)
+
+The daemon must call `chromium-browser` or `chromium` command.
+
 ## CRITICAL: Boot Flow
 
 ### GRUB Boot Menu (60s timeout)
@@ -91,8 +106,8 @@ Features:
 - All windows forced fullscreen
 - Chrome app_id rules for fullscreen
 
-### Chrome Launch
-Command: `google-chrome-stable`
+### Chromium Launch
+Command: `chromium-browser` (or `chromium`)
 Flags:
 - `--ozone-platform=wayland`
 - `--kiosk`
@@ -185,8 +200,8 @@ File: `/etc/NetworkManager/system-connections/wired.nmconnection`
 
 ## Troubleshooting
 
-### Chrome Not Starting
-1. Check if Chrome is installed: `which google-chrome-stable`
+### Chromium Not Starting
+1. Check if Chromium is installed: `which chromium-browser`
 2. Check hook permissions: `ls -la isobuild/config/hooks/normal/`
 3. Rebuild Docker image: `npm run build:docker`
 
@@ -210,5 +225,5 @@ File: `/etc/NetworkManager/system-connections/wired.nmconnection`
 - Base: Ubuntu 24.04 LTS (Noble)
 - Kernel: 6.8.0-90
 - Sway: From Ubuntu repos
-- Chrome: google-chrome-stable from dl.google.com
+- Chromium: From Debian sid/unstable or official Chromium builds
 - Deno: Latest (for daemon compilation)