Skip Office temp/lock files (~$) in folder watcher

Prevents the watcher from picking up ~$*.xlsx lock files created by
Excel, which would match the same ClickUp task and corrupt its status.

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

cheddahbot/scheduler.py

@@ -486,6 +486,9 @@ class Scheduler:
 
         for xlsx_path in xlsx_files:
             filename = xlsx_path.name
+            # Skip Office temp/lock files (e.g. ~$insert_molding.xlsx)
+            if filename.startswith("~$"):
+                continue
             kv_key = f"linkbuilding:watched:{filename}"
 
             # Skip completed/failed; retry "processing" (killed run) and "blocked" (missing field)