fix: capitalize watch-folder names to PascalCase-with-dashes on ingest

Folder names like "invoices" and "vendor-invoices" are now converted to
"Invoices" and "Vendor-Invoices" when the watcher auto-creates categories,
matching the naming convention enforced on user-created categories.

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

features/doc-service/app/services/file_watcher.py

@@ -11,7 +11,8 @@ Key design decisions:
 - Watch documents use user_id="watch" as a sentinel so they are visible to
   all authenticated users in the document list.
 - Subfolder names map to categories: a file at invoices/bill.pdf is assigned
-  to a "invoices" category (auto-created if needed).
+  to an "Invoices" category (auto-created if needed; folder name is converted
+  to PascalCase-with-dashes: "vendor-invoices" → "Vendor-Invoices").
 - Suggestions: if ai_folder_suggestion or ai_rename_suggestion are enabled,
   the relevant fields are set on the document after AI processing so users
   can confirm/reject from the UI.
@@ -21,6 +22,7 @@ Key design decisions:
 import asyncio
 import json
 import logging
+import re
 import uuid
 from pathlib import Path
 
@@ -66,7 +68,10 @@ async def ingest_file(path_str: str, watch_root: Path, config: dict) -> None:
         # Determine category from the first subfolder component
         try:
             rel = path.relative_to(watch_root)
-            folder_name = rel.parts[0] if len(rel.parts) > 1 else None
+            folder_name = (
+                "-".join(p.capitalize() for p in re.split(r"[-_\s]+", rel.parts[0]) if p)
+                if len(rel.parts) > 1 else None
+            )
         except ValueError:
             folder_name = None