feat: Discord/Slack/ntfy/Matrix targets, command templates, delete protection, email/matrix bots

- Discord, Slack, ntfy, Matrix notification target types with clients and dispatch
- MatrixBot model + API + frontend in Bots tab
- Command template system fully wired into all handler commands
- Default command templates seeded (EN/RU, 14 slots each)
- Command template editor with variables reference including child fields
- Delete protection on all 10 entity types (409 with consumer details)
- Provider type selector on template config forms
- Target type selector as dropdown with all 7 types
- Response template selector on command config form
- CLAUDE.md: mandatory server restart rule, child properties rule

packages/server/src/notify_bridge_server/api/target_receivers.py

@@ -31,13 +31,17 @@ class ReceiverUpdate(BaseModel):
 
 def _receiver_key(target_type: str, config: dict[str, Any]) -> str:
     """Derive a unique key for deduplication from receiver config."""
-    if target_type == "telegram":
-        return str(config.get("chat_id", ""))
-    elif target_type == "webhook":
-        return config.get("url", "")
-    elif target_type == "email":
-        return config.get("email", "")
-    return ""
+    key_fields = {
+        "telegram": "chat_id",
+        "webhook": "url",
+        "email": "email",
+        "discord": "webhook_url",
+        "slack": "webhook_url",
+        "ntfy": "topic",
+        "matrix": "room_id",
+    }
+    field = key_fields.get(target_type, "")
+    return str(config.get(field, "")) if field else ""
 
 
 @router.get("")