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/services/watcher.py

@@ -19,6 +19,7 @@ from ..database.engine import get_engine
 from ..database.models import (
     EmailBot,
     EventLog,
+    MatrixBot,
     NotificationTarget,
     NotificationTracker,
     NotificationTrackerState,
@@ -162,7 +163,7 @@ async def check_tracker(tracker_id: int) -> dict[str, Any]:
                         template_slots[event_key] = tmpl_text
 
             target_config = dict(target.config)
-            # Inject SMTP config for email targets from EmailBot
+            # Inject bot credentials for bot-backed target types
             if target.type == "email":
                 email_bot_id = target.config.get("email_bot_id")
                 if email_bot_id:
@@ -177,6 +178,13 @@ async def check_tracker(tracker_id: int) -> dict[str, Any]:
                             "from_name": email_bot.name,
                             "use_tls": email_bot.smtp_use_tls,
                         }
+            elif target.type == "matrix":
+                matrix_bot_id = target.config.get("matrix_bot_id")
+                if matrix_bot_id:
+                    matrix_bot = await session.get(MatrixBot, matrix_bot_id)
+                    if matrix_bot:
+                        target_config["homeserver_url"] = matrix_bot.homeserver_url
+                        target_config["access_token"] = matrix_bot.access_token
 
             link_data.append({
                 "target_type": target.type,