Wire up -o for stories; remove -o from status

- Extract _add_output_arg() helper; add it explicitly to summary, csv,
  and stories subparsers (removes it implicitly from status)
- _cmd_stories now honours args.output, redirecting print_stories output
  to the given file (same pattern as _cmd_summary)
- Update README with stories -o example

README.md

@@ -76,6 +76,7 @@ uv run timesheets csv -w --raw --joplin          # full week, no aggregation
 ```sh
 uv run timesheets stories --joplin               # today
 uv run timesheets stories -w --joplin            # full week
+uv run timesheets stories -w --joplin -o stories.md  # write to file
 ```
 
 ### status

src/timesheets/cli.py

@@ -83,6 +83,10 @@ def _add_shared_args(parser: argparse.ArgumentParser) -> None:
         ),
         default=None,
     )
+
+
+def _add_output_arg(parser: argparse.ArgumentParser) -> None:
+    """Add the -o/--output argument to a subparser."""
     parser.add_argument(
         "-o",
         "--output",
@@ -109,6 +113,7 @@ def build_parser() -> argparse.ArgumentParser:
         help="Print a human-readable summary of time spent per project.",
     )
     _add_shared_args(summary_parser)
+    _add_output_arg(summary_parser)
     summary_parser.add_argument(
         "--weekly",
         "-w",
@@ -132,6 +137,7 @@ def build_parser() -> argparse.ArgumentParser:
         help="Export timesheet entries as CSV.",
     )
     _add_shared_args(csv_parser)
+    _add_output_arg(csv_parser)
     csv_parser.add_argument(
         "--raw",
         action="store_true",
@@ -160,6 +166,7 @@ def build_parser() -> argparse.ArgumentParser:
         help="List stories worked on, grouped by project.",
     )
     _add_shared_args(stories_parser)
+    _add_output_arg(stories_parser)
     stories_parser.add_argument(
         "--weekly",
         "-w",
@@ -399,6 +406,16 @@ def _cmd_stories(args: argparse.Namespace, config: dict) -> None:
         return
 
     project_map = _resolve_project_map(args, config)
+    if args.output:
+        with open(args.output, "w", encoding="utf-8") as f:
+            old_stdout = sys.stdout
+            sys.stdout = f
+            try:
+                print_stories(rows, project_map)
+            finally:
+                sys.stdout = old_stdout
+        print(f"Written to {args.output}", file=sys.stderr)
+    else:
         print_stories(rows, project_map)