fix(dashboard): save validation feedback, public site light mode, global verify modal (#716)

* fix(dashboard): surface save errors, force public site light mode, global verify modal

- Show snackbar with first validation error when course update fails client-side validation
- Force light mode on public org-site pages; lesson player and dashboard keep theme selector
- Mount VerifyEmailModal in root layout for all authenticated routes; keep trigger=app email guard

Co-authored-by: Rotimi Best <rotimi-best@users.noreply.github.com>

* fix: instructor editor sync, auto-enroll after auth, email verification API

- Initialize instructor form from org fallbacks and batch metadata updates
- Auto-complete course enrollment after login/signup return from enroll page
- Block new org auto-enroll and course enroll until email is verified

Co-authored-by: Rotimi Best <rotimi-best@users.noreply.github.com>

* fix: address PR review on instructor setter, color scheme, auto-enroll

- Use existing setter with batched metadata.instructor updates in InstructorForm
- Allowlist public org-site paths so /lms and /courses/:id keep theme selector
- Auto-enroll logged-in users via Better Auth session; remove sessionStorage flow
- Retry enrollment after email verification without duplicate Join Course clicks

Co-authored-by: Rotimi Best <rotimi-best@users.noreply.github.com>

* fix: allow enrollment without verification; gate dashboard only

- Remove API email verification checks from enroll and auto-enroll flows
- Move VerifyEmailModal to (app) layout so public org-site pages stay usable
- Unverified users can enroll but hit the verification modal in LMS/dashboard

Co-authored-by: Rotimi Best <rotimi-best@users.noreply.github.com>

* fix: address PR feedback on verify modal, routes, instructor form

- Restore currentOrg.id guard on VerifyEmailModal open condition
- InstructorForm imports currentOrg directly instead of prop drilling
- Move public org-site light-mode route patterns to routes constants
- Reset enrollment attempt key on enroll failure to allow retry

Co-authored-by: Rotimi Best <rotimi-best@users.noreply.github.com>

---------

Co-authored-by: Cursor Agent <cursoragent@cursor.com>
Co-authored-by: Rotimi Best <rotimi-best@users.noreply.github.com>

apps/dashboard/src/lib/features/course/api/course.svelte.ts

@@ -440,6 +440,10 @@ export class CourseApi extends BaseApiWithErrors {
     const result = ZCourseUpdate.safeParse(fields);
     if (!result.success) {
       this.errors = mapZodErrorsToTranslations(result.error, 'course');
+      const firstError = this.errors.general ?? Object.values(this.errors).find(Boolean);
+      if (firstError) {
+        snackbar.error(firstError);
+      }
       return null;
     }