feat(triggershell): add Spotify app start command

Launches Spotify via systemd-run --user so it inherits the graphical
session environment (the triggershell service starts before the Wayland
session and lacks WAYLAND_DISPLAY/DISPLAY). Idempotent: no-op when
spotify.service is already active.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01LHvz6Nxkf9SU2EufjWZ3cG

triggershell.yml

@@ -354,6 +354,30 @@ scripts:
         passAs: arg
         argName: --zone
 
+  - id: spotify-start
+    name: "Spotify: Start App"
+    description: >-
+      Launch the Spotify desktop app on the local session. Does nothing if it is
+      already running (Spotify focuses its existing window).
+    command: bash
+    args:
+      - -c
+      - |
+        # triggershell.service starts before the graphical session, so its own
+        # environment has no WAYLAND_DISPLAY/DISPLAY and a stripped-down PATH.
+        # systemd-run --user launches Spotify from the user manager instead,
+        # which does carry the full graphical environment.
+        if systemctl --user --quiet is-active spotify.service; then
+          echo "Spotify is already running."
+          exit 0
+        fi
+        systemctl --user reset-failed spotify.service 2>/dev/null || true
+        exec systemd-run --user --collect --quiet --unit=spotify spotify-launcher
+      - spotify-start
+    cwd: ./
+    timeoutSeconds: 20
+    variables: []
+
   - id: system-shutdown
     name: "System: Shutdown"
     description: >-