v4.0.0 (#1719)

Release branch for 4.0.0.

server/.env.example

@@ -1,3 +1,8 @@
+# NOTE: variables are validated at startup (fail-fast). An UNSET or blank
+# variable always falls back to its default, but a variable that is set to a
+# malformed value (e.g. PORT=abc, SESSION_DURATION=bogus, DEMO_MODE=maybe)
+# aborts boot with a report of every offending variable.
+# Boolean switches accept true/false, 1/0, on/off and yes/no (any casing).
 PORT=3001 # Port to run the server on
 # HOST=0.0.0.0 # Bind address for the HTTP server. Only set this when running TREK from sources or via the Proxmox community script — never in Docker (the container handles binding).
 NODE_ENV=development # development = development mode; production = production mode
@@ -38,6 +43,9 @@ DEMO_MODE=false # Demo mode - resets data hourly
 
 # BACKUP_UPLOAD_LIMIT_MB=500 # Max size (MB) of a backup archive you can upload when restoring. Raise it if your backup exceeds 500 MB. If you sit behind a reverse proxy, raise its upload limit too (e.g. nginx client_max_body_size).
 
+# TREK_DB_JOURNAL_MODE=WAL # SQLite journal mode (DELETE, TRUNCATE, PERSIST, MEMORY, WAL, OFF). WAL is fastest and the right choice on local disk. Set DELETE if the data directory lives on network storage (Azure App Service, an SMB/NFS volume on a NAS) — WAL coordinates writers through a shared-memory file that those filesystems do not implement reliably. The mode is stored inside the database file, so it survives a restart; changing this applies on the next boot.
+# TREK_DB_SYNCHRONOUS=NORMAL # How hard SQLite flushes to disk (OFF, NORMAL, FULL, EXTRA). Defaults to NORMAL under WAL and FULL under any other journal mode — leave it alone unless you know why you want otherwise. Both variables fall back to their default (with a warning in the log) if the value is not a mode SQLite knows.
+
 # MCP_RATE_LIMIT=300 # Max MCP API requests per user per minute (default: 300)
 # MCP_MAX_SESSION_PER_USER=20 # Max concurrent MCP sessions per user (default: 20)