Week view flexibility: configurable day count, layout, and a CalDAV task list

- Day count (2-10, was fixed at 7) -- 5 days trims the weekend clutter
  without losing the grid format.
- Layout choice: days side by side (original behavior) or stacked
  vertically as full agenda-style sections (reuses _draw_agenda_day,
  same approach _build_today_tomorrow already used for a fixed 2 days).
- Optional task list (CalDAV VTODO collections only -- a plain ICS
  subscription doesn't meaningfully have one) that takes the space of
  one day slot instead of adding an extra one. Same owner-controls-
  their-own-data permission split as calendar sources: only the
  calendar's owner can point a frame's task list at it, but anyone
  linked to the frame can clear it.

Browse-offset paging now moves by N days (was hardcoded to weeks),
identical to the old behavior when days=7. Changing the day count
resets the browse offset, same reasoning as changing views already did.

server/app/routers/frame_pages.py

@@ -96,6 +96,24 @@ def _calendar_users_for_frame(db: Session, frame_id: int, viewer_id: int | None)
     return result
 
 
+def _tasks_source_info(db: Session, frame: Frame) -> dict | None:
+    """Whose CalDAV calendar this frame's week-view task list currently
+    pulls from, and its label -- for showing "using <name>'s Chores
+    list" to everyone linked, not just whoever set it. None if no
+    source is configured."""
+    if not frame.calendar_tasks_user_id or not frame.calendar_tasks_calendar_key:
+        return None
+    user = db.get(User, frame.calendar_tasks_user_id)
+    if user is None:
+        return None
+    label = frame.calendar_tasks_calendar_key
+    for c in (user.calendar_caldav_calendars or []):
+        if f"caldav:{c['href']}" == frame.calendar_tasks_calendar_key:
+            label = c.get("display_name") or label
+            break
+    return {"user_id": user.id, "display_name": user.display_name or user.username, "label": label}
+
+
 @router.get("/frames/{frame_id}/config", response_class=HTMLResponse)
 def frame_config_page(frame_id: int, request: Request, db: Session = Depends(get_db)):
     return _frame_page(
@@ -115,6 +133,10 @@ WEEK_START_LABELS = {0: "Monday", 1: "Tuesday", 2: "Wednesday", 3: "Thursday",
 @router.get("/frames/{frame_id}/calendar", response_class=HTMLResponse)
 def frame_calendar_page(frame_id: int, request: Request, db: Session = Depends(get_db)):
     viewer = current_user(request, db)
+    frame = db.get(Frame, frame_id)
+    viewer_task_calendars = []
+    if viewer is not None and frame is not None and can_view_frame(db, viewer, frame):
+        viewer_task_calendars = [c for c in _user_available_calendars(viewer) if c["key"].startswith("caldav:")]
     return _frame_page(
         request, db, frame_id, "frame_calendar.html", "calendar",
         calendar_views=CALENDAR_VIEW_LABELS,
@@ -123,6 +145,8 @@ def frame_calendar_page(frame_id: int, request: Request, db: Session = Depends(g
         calendar_color_labels=PALETTE_LABELS,
         default_palette_rgb=DEFAULT_PALETTE_RGB,
         palette_to_hex=palette_to_hex,
+        viewer_task_calendars=viewer_task_calendars,
+        tasks_source=_tasks_source_info(db, frame) if frame is not None else None,
     )