fix(env): align suggested DB pool size with MariaDB max_connections

The example .env suggested DATABASE_POOL_SIZE=150 and connection_limit=150.
MariaDB defaults max_connections to 151, so a single CMS instance could claim
the server's entire connection budget, starving the emulator and any second
instance. The README already documents a pool size of 25; the example now
matches and notes that DATABASE_POOL_SIZE is the value that actually applies.

.env.example

@@ -3,8 +3,13 @@
 # ==============================================================================
 
 # --- DATABASE (High Performance Pooling & Strict Timeouts) ---
-DATABASE_URL="mysql://user:password@localhost:3306/dbname?charset=utf8mb4&connection_limit=150&connect_timeout=5"
-DATABASE_POOL_SIZE=150
+# The pool size is governed by DATABASE_POOL_SIZE (src/lib/db.ts); the
+# `connection_limit` in the URL is only honoured by tools that read the URL
+# directly (drizzle-kit, scripts). Keep both in step and keep them well below
+# MariaDB's `max_connections` (151 by default) or the emulator and any second
+# CMS instance get "Too many connections". README §performance: pool size 25.
+DATABASE_URL="mysql://user:password@localhost:3306/dbname?charset=utf8mb4&connection_limit=25&connect_timeout=5"
+DATABASE_POOL_SIZE=25
 DATABASE_IDLE_TIMEOUT_MS=60000
 DATABASE_CONNECT_TIMEOUT_MS=5000