chore: remove Tailwind CSS build pipeline; replace with tailwind-compat.css shim

244 utility classes across 8 files (timetable pages, Modal, CCShapesPanel).
Rather than blind inline conversion, replace @tailwind directives with a
self-contained 230-line CSS shim covering all classes actually used.
Build passes. Shim entries can be converted to --cc-* tokens incrementally.

src/index.css

@@ -1,7 +1,6 @@
 /* src/index.css */
-@tailwind base;
-@tailwind components;
-@tailwind utilities;
+/* Tailwind removed — utility classes provided by tailwind-compat.css shim */
+@import './tailwind-compat.css';
 
 /* Base styles */
 html,