fix: convert asyncpg UUIDs to strings in web UI queries

worker/src/web.py

@@ -15,24 +15,37 @@ templates = Jinja2Templates(directory="templates")
 
 
 async def query(sql: str, *args) -> list:
-    """Execute a query and return rows as dicts."""
+    """Execute a query and return rows as dicts with UUIDs converted to strings."""
     try:
         pool = await get_pool()
         async with pool.acquire() as conn:
             rows = await conn.fetch(sql, *args)
-            return [dict(r) for r in rows]
+            result = []
+            for row in rows:
+                d = dict(row)
+                for k, v in d.items():
+                    if hasattr(v, 'hex'):  # asyncpg UUID
+                        d[k] = str(v)
+                result.append(d)
+            return result
     except Exception as e:
         logger.error("Database query error: %s", e)
         raise
 
 
 async def query_one(sql: str, *args) -> dict | None:
-    """Execute a query and return a single row as dict."""
+    """Execute a query and return a single row as dict with UUIDs converted to strings."""
     try:
         pool = await get_pool()
         async with pool.acquire() as conn:
             row = await conn.fetchrow(sql, *args)
-            return dict(row) if row else None
+            if not row:
+                return None
+            d = dict(row)
+            for k, v in d.items():
+                if hasattr(v, 'hex'):  # asyncpg UUID
+                    d[k] = str(v)
+            return d
     except Exception as e:
         logger.error("Database query error: %s", e)
         raise