feat: live ISO — nix daemon mode, autologin fix, GPU detection, app stack

- Switch nix from single-user to daemon mode (trusted-users = root live);
  Void socket at /var/nix/daemon-socket/socket confirmed
- Fix lightdm autologin: use session-wrapper=/etc/lightdm/Xsession (Void
  lightdm 1.32 has no lightdm-session binary)
- Fix session env: LIBGL_ALWAYS_SOFTWARE=1 via profile.d (session-env=
  is unsupported in this lightdm version)
- GPU auto-detection at boot: VIRT→software GL, NVIDIA PRIME offload,
  Intel/AMD/generic→modesetting
- Add nix-daemon to live runsvdir/default; remove unsupported -S mklive flag
- first-login.sh: install Claude Code + nix user packages (google-chrome,
  spotify, discord, localsend, mission-center) + NVM/node + VS Code exts
- build-live-iso.sh: write nix-packages.list from NIX_USER_PACKAGES
- postinstall.sh: fix nix-daemon socket path to /var/nix/daemon-socket/socket
- Dockerfile: add dconf-cli for build-time dconf compile
- _inner-build-live.sh: use correct 'dconf compile' API (not 'dconf update')
- .gitignore: add build/live-includes/ (generated staging tree)
- docs/LIVE_ISO.md: document all findings, gotchas and architecture

iso/_inner-build-live.sh

@@ -28,10 +28,12 @@ command -v xbps-install.static >/dev/null \
 mkdir -p "$(dirname "$OUT_ISO")"
 
 # Compile dconf system-db inside the include dir so it ships compiled.
+# Debian's dconf-cli provides 'dconf compile <output_db> <keyfile_dir>'.
 if command -v dconf >/dev/null 2>&1 && [[ -d "$INCLUDE_DIR/etc/dconf/db/local.d" ]]; then
-    DCONF_PROFILE_PATH="$INCLUDE_DIR/etc/dconf/profile" \
-    DCONF_SYSTEM_DB_PATH="$INCLUDE_DIR/etc/dconf/db" \
-    dconf update "$INCLUDE_DIR/etc/dconf/db" 2>/dev/null || true
+    dconf compile "$INCLUDE_DIR/etc/dconf/db/local" \
+                  "$INCLUDE_DIR/etc/dconf/db/local.d" 2>/dev/null \
+    && echo "dconf: compiled system-db/local" \
+    || echo "dconf: compile failed (non-fatal)"
 fi
 
 cd "$MKLIVE_DIR"
@@ -52,6 +54,7 @@ trap _cleanup_mklive_builds EXIT
 ./mklive.sh \
     -a "$ARCH" \
     -r "$REPO_URL" \
+    -r "${REPO_URL%/current}/current/nonfree" \
     -c "$CACHE_DIR/xbps-live-pkgs" \
     -H "$CACHE_DIR/xbps-host-pkgs" \
     -k "$KEYMAP" \