Add manual backup trigger endpoint

POST /api/v1/system/auto-backup/trigger creates a backup on demand
and returns the created file info (filename, size, timestamp).

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

TODO.md

@@ -41,7 +41,7 @@ Priority: `P1` quick win · `P2` moderate · `P3` large effort
 ## Code Health
 
 - [ ] `P1` **"Start All" targets button** — "Stop All" exists but "Start All" is missing
-- [ ] `P2` **Manual backup trigger endpoint** — `POST /system/auto-backup/trigger` (~5 lines)
+- [x] `P2` **Manual backup trigger endpoint** — `POST /system/auto-backup/trigger` (~5 lines)
 - [ ] `P2` **Scene snapshot should capture device brightness** — `software_brightness` not saved/restored
 - [ ] `P2` **Distinguish "crashed" vs "stopped" in dashboard** — `metrics.last_error` is already populated
 - [ ] `P3` **Home Assistant MQTT discovery** — publish auto-discovery payloads; MQTT infra already exists

server/src/wled_controller/api/routes/system.py

@@ -489,6 +489,16 @@ async def update_auto_backup_settings(
     )
 
 
+@router.post("/api/v1/system/auto-backup/trigger", tags=["System"])
+async def trigger_backup(
+    _: AuthRequired,
+    engine: AutoBackupEngine = Depends(get_auto_backup_engine),
+):
+    """Manually trigger a backup now."""
+    backup = await engine.trigger_backup()
+    return {"status": "ok", "backup": backup}
+
+
 @router.get(
     "/api/v1/system/backups",
     response_model=BackupListResponse,

server/src/wled_controller/core/backup/auto_backup.py

@@ -211,6 +211,14 @@ class AutoBackupEngine:
             raise ValueError("Invalid filename")
         return target
 
+    async def trigger_backup(self) -> dict:
+        """Manually trigger a backup and prune old ones. Returns the created backup info."""
+        await self._perform_backup()
+        self._prune_old_backups()
+        # Return the most recent backup entry
+        backups = self.list_backups()
+        return backups[0] if backups else {}
+
     def delete_backup(self, filename: str) -> None:
         target = self._safe_backup_path(filename)
         if not target.exists():