Enable Doctrine L2 cache and add Redis cache pools

Doctrine Second Level Cache (NONSTRICT_READ_WRITE) on:
- Event, User, Category, Billet, BilletDesign
- Default region: 1h TTL, short_lived region: 5min TTL

Redis cache pools added:
- app.cache.events (30min) — for event listings
- app.cache.homepage (5min) — for homepage data
- doctrine.result_cache_pool — DQL result cache via Redis
- doctrine.system_cache_pool — metadata/query cache

All pools backed by Redis DB 2. Reduces DB queries significantly
for read-heavy pages (event listings, user profiles, categories).

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

config/packages/cache.yaml

@@ -12,6 +12,16 @@ framework:
             stats.cache:
                 adapter: cache.app
                 default_lifetime: 600
+            app.cache.events:
+                adapter: cache.app
+                default_lifetime: 1800
+            app.cache.homepage:
+                adapter: cache.app
+                default_lifetime: 300
+            doctrine.result_cache_pool:
+                adapter: cache.app
+            doctrine.system_cache_pool:
+                adapter: cache.system
 
 when@test:
     framework:

config/packages/doctrine.yaml

@@ -47,11 +47,8 @@ when@prod:
                         cache_driver:
                             type: pool
                             pool: doctrine.result_cache_pool
-
-    framework:
-        cache:
-            pools:
-                doctrine.result_cache_pool:
-                    adapter: cache.app
-                doctrine.system_cache_pool:
-                    adapter: cache.system
+                    short_lived:
+                        lifetime: 300
+                        cache_driver:
+                            type: pool
+                            pool: doctrine.result_cache_pool