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

CHANGELOG.md

@@ -1,5 +1,13 @@
 # Changelog
 
+## v1.1.0 — 2026-03-13
+
+### Changes
+
+- **Cancelled course support** — "Managing Growing Companies" (Summer Elective Set 2) is marked as cancelled and rendered with strikethrough, greyed-out styling, and a "(Cancelled)" label; it is excluded from solver computations and decision tree enumeration
+- **Duplicate course prevention** — courses that appear in multiple elective sets (e.g., "Global Immersion Experience II" in Spring Set 1 and Summer Set 1, "The Financial Services Industry" in Spring Set 2 and Fall Set 4) are now linked; selecting one automatically disables and excludes its duplicate from selection and solver calculations, shown with an "(Already selected)" label
+- **Credit bar tick marks** — specialization progress bars now display light vertical tick marks at 2.5-credit intervals for visual scale reference, layered above bar fills with the 9.0 threshold marker remaining visually distinct
+
 ## v1.0.0 — 2026-02-28
 
 Initial release of the EMBA Specialization Solver.