Skip Not-Started tasks that are already assigned to someone

A task carrying an "Assigned to" avatar in the Planner grid has been picked
up by a person, so its attachments must not be downloaded and its status must
not be moved to In Progress. Until now the only filter was percentComplete
== 0, so an assigned task with an attachment was downloaded like any other —
on the Balboa Nursing and Rehab plan that was one of the two "Facesheets
Needed (GG)" tasks assigned to Dr. Mark Lukasik and Adina Smets.

- _not_started_tasks() now selects `assignments` as well.
- _task_assignee_ids()/_resolve_user_names(): the assignee check runs before
  the task-details call, so an assigned task costs no extra Graph request;
  display names are resolved once per user and cached for the run, falling
  back to the raw ID when the lookup fails.
- Summary workbook gains a "Tasks Skipped (Assigned)" column and a second
  "Tasks" sheet with one row per task — facility, task name, assigned to,
  attachment count, Downloaded Yes/No and the reason — so a skip can be
  explained without reading the log.
- New "All assigned — skipped" facility status, distinct from "No attachments".

scripts/probe_assignments.py is the read-only probe used to confirm the rule
against the live plan before changing behaviour.

Verified on Balboa Nursing and Rehab: 4 Not Started -> 8.24.26 and 8.21.26
downloaded (unassigned), both Facesheets Needed (GG) skipped. 110 tests pass
(tests/test_uipath_pilot.py and tests/test_config.py fail on this checkout for
pre-existing, unrelated reasons).

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

scripts/probe_assignments.py

@@ -0,0 +1,88 @@
+#!/usr/bin/env python3
+"""
+Read-only probe: for one plan, list every Not-Started task with its assignee
+count and attachment count, so the "skip assigned tasks" rule can be validated
+against what the Planner grid shows before any behaviour is changed.
+
+Downloads nothing and never PATCHes a task — safe against production Planner.
+
+Run:  .venv\\Scripts\\python scripts\\probe_assignments.py --facility "Balboa"
+"""
+from __future__ import annotations
+
+import argparse
+import logging
+import sys
+from pathlib import Path
+
+ROOT = Path(__file__).resolve().parent.parent
+SRC = ROOT / "src"
+for p in (str(ROOT), str(SRC)):
+    if p not in sys.path:
+        sys.path.insert(0, p)
+
+from config import read_app_config  # noqa: E402
+from onedrive_planner_http import (  # noqa: E402
+    _build_client,
+    _discover_all_plans,
+    _get_paged,
+    _login_with_retry,
+    _match_plan,
+    _task_file_urls,
+)
+
+
+def main() -> int:
+    ap = argparse.ArgumentParser()
+    ap.add_argument("--facility", required=True, help="facility / plan name fragment")
+    ap.add_argument("--headed", action="store_true")
+    args = ap.parse_args()
+
+    logging.basicConfig(
+        level=logging.INFO,
+        format="%(asctime)s %(levelname)-7s %(message)s",
+        stream=sys.stdout,
+    )
+
+    cfg = read_app_config()
+    token, _ = _login_with_retry(cfg, headless=not args.headed)
+    client = _build_client(cfg, token)
+
+    plans = _discover_all_plans(client, cfg)
+    plan = _match_plan(plans, args.facility)
+    if not plan:
+        print(f"no plan matched {args.facility!r}")
+        return 1
+
+    print(f"\nplan: {plan.get('title')!r}\n")
+    tasks = _get_paged(
+        client,
+        f"planner/plans/{plan['id']}/tasks",
+        cfg,
+        **{"$select": "id,title,percentComplete,assignments,orderHint"},
+    )
+
+    print(f"{'%':>4}  {'assignees':>9}  {'files':>5}  title")
+    print("-" * 78)
+    would_download = would_skip = 0
+    for t in tasks:
+        pct = t.get("percentComplete") or 0
+        if pct != 0:
+            continue
+        assignees = len(t.get("assignments") or {})
+        n_files = len(_task_file_urls(client, t["id"], cfg))
+        print(f"{pct:>4}  {assignees:>9}  {n_files:>5}  {(t.get('title') or '')[:50]}")
+        if n_files:
+            if assignees:
+                would_skip += 1
+            else:
+                would_download += 1
+
+    print("-" * 78)
+    print(f"With the 'skip assigned' rule: {would_download} would download, "
+          f"{would_skip} would skip (attachment-bearing tasks only)")
+    return 0
+
+
+if __name__ == "__main__":
+    raise SystemExit(main())