fix: wrap classic Home screen in a sized container, separate dial arc radii

Two bugs found on first hardware test:

1. page_home placed all widgets directly on the page with no sized
   wrapper container, unlike every other page in this codebase (which
   all wrap content in an explicit width/height obj before using
   align:). The dial and its siblings rendered tiny and pinned to the
   top-left instead of filling/centering on the real 1024x600 screen.
   Wrapped all of page_home's content in a width:100%/height:100% obj,
   matching the established pattern.

2. heat_arc and cool_arc were both adjustable:true at the identical
   400x400 size, so their rings occupied the same physical pixels.
   LVGL hit-tests arcs by distance from center, so a shared radius is
   touch-ambiguous, and the topmost widget (cool_arc, declared last)
   won every touch regardless of where on the ring you tapped. Shrunk
   cool_arc to 360x360 so the two rings are physically distinguishable
   by touch position.

firmware/components/display-classic.yaml

@@ -6,6 +6,14 @@ lvgl:
     - touch_gt911
   pages:
     - id: page_home
+      widgets:
+        - obj:
+            width: 100%
+            height: 100%
+            pad_all: 0
+            border_width: 0
+            outline_width: 0
+            scrollable: false
             widgets:
               - label:
                   align: top_left
@@ -118,8 +126,11 @@ lvgl:
                   id: cool_arc
                   align: center
                   y: -20
-            width: 400px
-            height: 400px
+                  width: 360px    # smaller radius than heat_arc (400px) so the two rings occupy
+                  height: 360px   # different physical pixels — LVGL hit-tests arcs by distance
+                                  # from center, and two arcs at the same radius are touch-ambiguous;
+                                  # the topmost one (this one, declared last) always wins regardless
+                                  # of where along the ring you actually tap
                   start_angle: 315
                   end_angle: 225
                   mode: REVERSE