Add ESPNow preset send backend support

Implement ESPNow helper model, WebSocket forwarding, and /presets/send endpoint that chunks and broadcasts presets to devices.

src/controllers/preset.py

@@ -1,5 +1,7 @@
 from microdot import Microdot
 from models.preset import Preset
+from models.espnow import ESPNow
+from util.espnow_message import build_message, build_preset_dict
 import json
 
 controller = Microdot()
@@ -48,3 +50,79 @@ async def delete_preset(request, id):
     if presets.delete(id):
         return json.dumps({"message": "Preset deleted successfully"}), 200
     return json.dumps({"error": "Preset not found"}), 404
+
+
+@controller.post('/send')
+async def send_presets(request):
+    """
+    Send one or more presets over ESPNow.
+
+    Body JSON:
+        {"preset_ids": ["1", "2", ...]}  or  {"ids": ["1", "2", ...]}
+
+    The controller:
+      - looks up each preset in the Preset model
+      - converts them to API-compliant format
+      - splits into <= 240-byte ESPNow messages
+      - sends each message to all configured ESPNow peers.
+    """
+    try:
+        data = request.json or {}
+    except Exception:
+        return json.dumps({"error": "Invalid JSON"}), 400, {'Content-Type': 'application/json'}
+
+    preset_ids = data.get('preset_ids') or data.get('ids')
+    if not isinstance(preset_ids, list) or not preset_ids:
+        return json.dumps({"error": "preset_ids must be a non-empty list"}), 400, {'Content-Type': 'application/json'}
+
+    # Build API-compliant preset map keyed by preset name
+    presets_by_name = {}
+    for pid in preset_ids:
+        preset_data = presets.read(str(pid))
+        if not preset_data:
+            continue
+        name_key = preset_data.get('name') or str(pid)
+        presets_by_name[name_key] = build_preset_dict(preset_data)
+
+    if not presets_by_name:
+        return json.dumps({"error": "No matching presets found"}), 404, {'Content-Type': 'application/json'}
+
+    # Use shared ESPNow singleton
+    esp = ESPNow()
+
+    async def send_chunk(chunk_presets):
+        msg = build_message(presets=chunk_presets)
+        await esp.send(msg)
+
+    MAX_BYTES = 240
+    entries = list(presets_by_name.items())
+    total_presets = len(entries)
+    messages_sent = 0
+
+    batch = {}
+    last_msg = None
+    for name, preset_obj in entries:
+        test_batch = dict(batch)
+        test_batch[name] = preset_obj
+        test_msg = build_message(presets=test_batch)
+        size = len(test_msg)
+
+        if size <= MAX_BYTES or not batch:
+            batch = test_batch
+            last_msg = test_msg
+        else:
+            await send_chunk(batch)
+            messages_sent += 1
+            batch = {name: preset_obj}
+            last_msg = build_message(presets=batch)
+
+    if batch:
+        await send_chunk(batch)
+        messages_sent += 1
+
+    return json.dumps({
+        "message": "Presets sent via ESPNow",
+        "presets_sent": total_presets,
+        "messages_sent": messages_sent
+    }), 200, {'Content-Type': 'application/json'}
+