v1.1.0: Add cancelled course, duplicate prevention, and credit bar ticks

- Mark "Managing Growing Companies" as cancelled with visual indicator and solver exclusion
- Prevent selecting duplicate courses across elective sets (e.g., same course in Spring and Summer)
- Add 2.5-credit interval tick marks to specialization progress bars
- Bump version to 1.1.0 with date display in UI header

app/src/data/courses.ts

@@ -110,6 +110,7 @@ export const COURSES: Course[] = [
   // === Summer Elective Set 2 ===
   {
     id: 'sum2-managing-growing', name: 'Managing Growing Companies', setId: 'sum2',
+    cancelled: true,
     qualifications: [
       { specId: 'ENT', marker: 'standard' }, { specId: 'LCM', marker: 'standard' },
       { specId: 'MGT', marker: 'standard' }, { specId: 'STR', marker: 'S1' },