Move mode picker below device status bar; fix invisible calendar lines; add CalDAV calendar support

Calendar rule/grid lines were light gray, which dithers away to
near-invisible on the 6-color e-ink palette -- now black.

CalDAV accounts (Nextcloud, Fastmail, iCloud, ...) can now be linked
alongside the existing single ICS subscription, since one account can
expose several calendars. A frame's Calendar tab now lists calendars
per person rather than one opt-in per person: your own row shows every
calendar you have available with a full add/remove toggle, while other
linked users' rows show only calendars they've included, toggleable
off (mute) but not on -- only a calendar's owner can add it to a
shared frame. FrameCalendar replaces the old single-boolean
UserFrame.calendar_included; existing opt-ins are migrated forward.

server/app/migration.py

@@ -110,6 +110,41 @@ def _migration_8(conn) -> None:
 
 
 
+def _migration_9(conn) -> None:
+    """CalDAV support alongside the plain ICS subscription (see
+    caldav_client.py), and the frame_calendars table that replaces
+    user_frames.calendar_included now that one account (CalDAV) can
+    expose more than one calendar -- see models.py's FrameCalendar.
+    Existing single-calendar opt-ins are carried forward as "ics" rows
+    before the old column is dropped, so nobody's frame goes silently
+    calendar-less after this migration."""
+    conn.execute(text("ALTER TABLE users ADD COLUMN calendar_caldav_url TEXT NOT NULL DEFAULT ''"))
+    conn.execute(text("ALTER TABLE users ADD COLUMN calendar_caldav_username TEXT NOT NULL DEFAULT ''"))
+    conn.execute(text("ALTER TABLE users ADD COLUMN calendar_caldav_password TEXT NOT NULL DEFAULT ''"))
+    conn.execute(text("ALTER TABLE users ADD COLUMN calendar_caldav_calendars TEXT"))
+    conn.execute(text("ALTER TABLE users ADD COLUMN calendar_caldav_checked_at REAL NOT NULL DEFAULT 0.0"))
+
+    conn.execute(text(
+        "CREATE TABLE frame_calendars ("
+        "id INTEGER PRIMARY KEY, "
+        "frame_id INTEGER NOT NULL REFERENCES frames(id) ON DELETE CASCADE, "
+        "user_id INTEGER NOT NULL REFERENCES users(id) ON DELETE CASCADE, "
+        "calendar_key TEXT NOT NULL, "
+        "calendar_label TEXT NOT NULL DEFAULT '', "
+        "included INTEGER NOT NULL DEFAULT 1)"
+    ))
+    conn.execute(text(
+        "CREATE UNIQUE INDEX ix_frame_calendars_unique ON frame_calendars (frame_id, user_id, calendar_key)"
+    ))
+    conn.execute(text(
+        "INSERT INTO frame_calendars (frame_id, user_id, calendar_key, calendar_label, included) "
+        "SELECT uf.frame_id, uf.user_id, 'ics', 'My calendar', 1 "
+        "FROM user_frames uf JOIN users u ON u.id = uf.user_id "
+        "WHERE uf.calendar_included = 1 AND u.calendar_ics_url != ''"
+    ))
+    conn.execute(text("ALTER TABLE user_frames DROP COLUMN calendar_included"))
+
+
 MIGRATIONS = [
     (1, _migration_1),
     (2, _migration_2),
@@ -119,6 +154,7 @@ MIGRATIONS = [
     (6, _migration_6),
     (7, _migration_7),
     (8, _migration_8),
+    (9, _migration_9),
 ]