fix(dashboard): cache org stats in Redis with versioned invalidation (#883)

* fix(dashboard): cache org stats in Redis with versioned invalidation

Replace the never-expiring process-local cache in the org dashboard page
load with API-side Redis caching keyed per org. A version stamp prevents
slow reads from writing pre-purge data back into the cache.

Invalidate on course create/update/delete, student enroll/remove, certificate
claim, and progress reset. Remove the dashboard SSR module cache so every
page load reads through the API cache layer.

Fixes #852

Co-authored-by: Rotimi Best <[email protected]>

* fix(dashboard): address PR review on stats cache invalidation

- Validate bust via ZDashStats instead of raw query access
- Use import type for OrganisationAnalytics
- Resolve orgId before course delete so invalidation is reliable
- Invalidate immediately after persisted writes, before fallible side effects
- Invalidate on member role changes and program course access enrollment

Co-authored-by: Rotimi Best <[email protected]>

* fix(dashboard): complete stats cache invalidation coverage

Wire org stats cache purge on lesson completion (manual toggle and
video-watch auto-complete) so topCourses completion percentages stay
fresh. Harden bulk member adds with sequential inserts and a finally
invalidation boundary, and only purge org invite enrollments when new
group memberships were actually inserted.

Co-authored-by: Rotimi Best <[email protected]>

* fix(core): make lesson completion stats purge best-effort

Wrap org stats cache invalidation in try/catch so a lookup or Redis
failure cannot turn a successful lesson completion into a 500.

Co-authored-by: Rotimi Best <[email protected]>

* fix(dashboard): keep org stats cache through lesson completion

Lesson complete is a high-frequency event and usually does not change
the rounded dashboard percentages. Rely on a 10 minute TTL instead of
purging the snapshot on every completion.

Co-authored-by: Rotimi Best <[email protected]>

* docs: explain how admin dashboard numbers are calculated

Add a user-facing guide covering headline counts, top courses,
certificates, login activity, and when the 10 minute snapshot refreshes.

Co-authored-by: Rotimi Best <[email protected]>

---------

packages/utils/src/validation/dash/stats.ts

@@ -3,7 +3,11 @@ import * as z from 'zod';
 export const ZDashStats = z
   .object({
     orgId: z.string().optional(),
-    siteName: z.string().optional()
+    siteName: z.string().optional(),
+    bust: z
+      .enum(['0', '1'])
+      .optional()
+      .transform((value) => value === '1')
   })
   .refine((v) => !!(v.orgId || v.siteName), {
     message: 'Either orgId or siteName is required'