Add HTTP trigger endpoint for on-demand frame refresh

Lightweight server on port 8080 that accepts POST /refresh and
starts birdframe.service. Runs as a systemd service so the web
UI's Refresh Now button can trigger immediate display updates.

Co-Authored-By: Claude Opus 4 <noreply@anthropic.com>

frame/trigger.py

@@ -0,0 +1,36 @@
+#!/usr/bin/env python3
+"""Tiny HTTP server that triggers a birdframe refresh on demand."""
+
+import http.server
+import subprocess
+import json
+
+PORT = 8080
+
+class Handler(http.server.BaseHTTPRequestHandler):
+    def do_POST(self):
+        if self.path == "/refresh":
+            subprocess.Popen(["systemctl", "start", "birdframe.service"])
+            self.send_response(200)
+            self.send_header("Content-Type", "application/json")
+            self.send_header("Access-Control-Allow-Origin", "*")
+            self.end_headers()
+            self.wfile.write(json.dumps({"status": "triggered"}).encode())
+        else:
+            self.send_response(404)
+            self.end_headers()
+
+    def do_OPTIONS(self):
+        self.send_response(204)
+        self.send_header("Access-Control-Allow-Origin", "*")
+        self.send_header("Access-Control-Allow-Methods", "POST, OPTIONS")
+        self.send_header("Access-Control-Allow-Headers", "Content-Type")
+        self.end_headers()
+
+    def log_message(self, fmt, *args):
+        pass
+
+if __name__ == "__main__":
+    server = http.server.HTTPServer(("0.0.0.0", PORT), Handler)
+    print(f"frame-trigger listening on :{PORT}")
+    server.serve_forever()