Bump PocketBase to 0.40.0

Also update the README version references, which were still on 0.39.9.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

.env.example

@@ -4,7 +4,7 @@
 
 # ── General ───────────────────────────────────────────────────────────
 # PocketBase version to build (must match a published release tag, without the leading "v")
-PB_VERSION=0.39.10
+PB_VERSION=0.40.0
 
 # Name of the running container
 CONTAINER_NAME=pocketbase