Disambiguate same-type widgets in the button-assignment dropdowns

Two widgets of the same type (e.g. two Photos widgets) both showed up
as plain "Photos" with no way to tell which was which. The buttons API
now includes each widget's grid placement plus the frame's grid dims;
the UI derives a rough position ("top-left", "right", etc.) from that
and only appends a number+position suffix when a type actually
repeats on the frame, leaving the common single-widget-per-type case
unchanged.

server/app/routers/api_frames.py

@@ -259,7 +259,15 @@ def api_buttons_get(frame: Frame = Depends(require_frame_view), db: Session = De
     """Everything the button-assignment UI needs in one call: every
     widget on the frame with the actions its type supports (see
     app/widgets/*.py's ACTIONS/ACTION_LABELS), plus each button's current
-    ordered list of (widget, action) bindings."""
+    ordered list of (widget, action) bindings.
+
+    Includes each widget's placement (x/y/w/h) and the frame's grid
+    dimensions -- two widgets of the same type otherwise look identical
+    in the assignment UI's dropdowns (both just say "Photos"); the
+    client derives a position label ("top-left" etc.) from this to tell
+    them apart, the same way you'd tell them apart by eye on the Layout
+    canvas."""
+    cols, rows = grid.grid_dims(frame.orientation)
     widgets = db.scalars(
         select(Widget).where(Widget.frame_id == frame.id).order_by(Widget.sort_order)
     ).all()
@@ -267,6 +275,7 @@ def api_buttons_get(frame: Frame = Depends(require_frame_view), db: Session = De
         {
             "id": w.id,
             "widget_type": w.widget_type,
+            "x": w.x, "y": w.y, "w": w.w, "h": w.h,
             "actions": [
                 {"action": action, "label": label}
                 for action, label in getattr(WIDGET_TYPES.get(w.widget_type), "ACTION_LABELS", {}).items()
@@ -274,7 +283,7 @@ def api_buttons_get(frame: Frame = Depends(require_frame_view), db: Session = De
         }
         for w in widgets
     ]
-    result = {"widgets": widget_options}
+    result = {"widgets": widget_options, "grid": {"cols": cols, "rows": rows}}
     for button in BUTTONS:
         rows = db.scalars(
             select(FrameButtonAction)