version: bump to 1.10.13 AccessibleUI

Session complete with accessibility and UI/UX improvements:
- Enhanced OLED color palette (better contrast ratios)
- Integrated Fira typography system
- Added 100+ cursor-pointer and focus states
- Removed all uppercase text-transform
- Improved footer visibility
- All changes verified with successful build

No breaking changes. Ready for next development phase.

frontend/VERSION.json

@@ -1,6 +1,6 @@
 {
-  "version": "1.10.12",
-  "last_build": "2026-04-17-1112",
-  "codename": "StableFlow",
-  "commit": "91e986b3"
-}
+  "version": "1.10.13",
+  "last_build": "2026-04-17-1430",
+  "codename": "AccessibleUI",
+  "commit": "f28052ea"
+}