feat(selfpaced): student-facing My Programs dashboard

- ProgramsTab.jsx: Active/Completed programs, real progress, deterministic Continue Learning
  (reuses the same launch/poll pattern MyLearningTab already established), entitlement-blocked
  states shown with a real reason, never a silent dead end.
- StudentDashboard.jsx: new My Programs tab. api.js: programs/program/launchProgram.

frontend/src/platform/api.js

@@ -119,4 +119,9 @@ export const api = {
   leaveClassroom: (id) => mutate(`/api/classroom/${id}/leave`),
   classroomHeartbeat: (id) => mutate(`/api/classroom/${id}/heartbeat`),
   requestHelp: (id, category, message) => mutate(`/api/classroom/${id}/help-request`, { category, message }),
+
+  // ── Phase 5B: self-paced programs ────────────────────────────────────────────────────────
+  programs: () => fetch('/api/student/programs').then(json),
+  program: (enrollmentId) => fetch(`/api/student/programs/${enrollmentId}`).then(json),
+  launchProgram: (enrollmentId) => mutate(`/api/student/programs/${enrollmentId}/launch`),
 }