fix(immich): improve thumbnail loading performance on iOS app

- Bump immich-server memory 1700Mi/2500Mi → 2000Mi/3500Mi to prevent OOM kills
- Disable anti-AI middleware chain for Immich (removes 3 unnecessary ForwardAuth
  hops per request — Immich content is behind auth, not crawlable)
- Double rate limit to 200 avg / 2000 burst for fast-scroll thumbnail requests
- Fix ImmichFrame image tag (1.7.4 → v1.0.32.0)
- Add PostgreSQL vector search prewarming and tuning (SSD storage type,
  init container for override conf, postStart pg_prewarm)

stacks/traefik/modules/traefik/middleware.tf

@@ -244,8 +244,8 @@ resource "kubernetes_manifest" "middleware_immich_rate_limit" {
     }
     spec = {
       rateLimit = {
-        average = 100
-        burst   = 1000
+        average = 200
+        burst   = 2000
       }
     }
   }