Restyle main page: collapsible sections, theme-aware ticks, UI polish

- Make Devices and Displays sections collapsible with persistent state
- Move WLED config tip from footer to under Devices heading
- Add theme-aware colors for calibration canvas ticks and chevrons
- Rename sections to "Devices" and "Displays" with emoji prefix icons
- Fix display layout scaling to fill available space
- Remove unused footer-tip and modal code

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

server/src/wled_controller/static/locales/en.json

@@ -19,7 +19,7 @@
   "auth.logout.success": "Logged out successfully",
   "auth.please_login": "Please login to view",
   "displays.title": "Available Displays",
-  "displays.layout": "Display Layout",
+  "displays.layout": "\uD83D\uDDA5\uFE0F Displays",
   "displays.information": "Display Information",
   "displays.legend.primary": "Primary Display",
   "displays.legend.secondary": "Secondary Display",
@@ -32,7 +32,7 @@
   "displays.loading": "Loading displays...",
   "displays.none": "No displays available",
   "displays.failed": "Failed to load displays",
-  "devices.title": "WLED Devices",
+  "devices.title": "\uD83D\uDCA1 Devices",
   "devices.add": "Add New Device",
   "devices.loading": "Loading devices...",
   "devices.none": "No devices configured",