feat(bot): implement conversational input, forwarded message auto-detection, and button-driven channel config

db/repository.py

@@ -48,12 +48,22 @@ class Repository:
             rows = await conn.fetch("SELECT * FROM sources WHERE is_active = TRUE ORDER BY id ASC;")
             return [SourceChannel(**dict(r)) for r in rows]
 
-    async def get_source_by_channel_id(self, channel_id: int) -> Optional[SourceChannel]:
+    async def get_source_by_id(self, source_id: int) -> Optional[SourceChannel]:
         pool = await self._get_pool()
         async with pool.acquire() as conn:
-            row = await conn.fetchrow("SELECT * FROM sources WHERE channel_id = $1;", channel_id)
+            row = await conn.fetchrow("SELECT * FROM sources WHERE id = $1;", source_id)
             return SourceChannel(**dict(row)) if row else None
 
+    async def delete_source(self, source_id: int) -> None:
+        pool = await self._get_pool()
+        async with pool.acquire() as conn:
+            await conn.execute("UPDATE sources SET is_active = FALSE WHERE id = $1;", source_id)
+
+    async def delete_target(self, target_id: int) -> None:
+        pool = await self._get_pool()
+        async with pool.acquire() as conn:
+            await conn.execute("UPDATE targets SET is_active = FALSE WHERE id = $1;", target_id)
+
     # --- Target Channels ---
     async def add_target(
         self,