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/workers/decisionTree.worker.ts

@@ -7,6 +7,7 @@ export interface WorkerRequest {
   openSetIds: string[];
   ranking: string[];
   mode: OptimizationMode;
+  excludedCourseIds?: string[];
 }
 
 export interface WorkerResponse {
@@ -16,7 +17,10 @@ export interface WorkerResponse {
 }
 
 self.onmessage = (e: MessageEvent<WorkerRequest>) => {
-  const { pinnedCourseIds, openSetIds, ranking, mode } = e.data;
+  const { pinnedCourseIds, openSetIds, ranking, mode, excludedCourseIds } = e.data;
+  const excludedSet = excludedCourseIds && excludedCourseIds.length > 0
+    ? new Set(excludedCourseIds)
+    : undefined;
 
   const analyses = analyzeDecisionTree(
     pinnedCourseIds,
@@ -28,6 +32,7 @@ self.onmessage = (e: MessageEvent<WorkerRequest>) => {
       const response: WorkerResponse = { type: 'setComplete', analysis };
       self.postMessage(response);
     },
+    excludedSet,
   );
 
   // Final result with sorted analyses