feat: web setup wizard + admin config/state dir split (#226)

.env.example

@@ -78,10 +78,27 @@ JMAP_SERVER_URL=https://your-jmap-server.com
 # Admin Dashboard Data
 # =============================================================================
 
-# Directory for admin dashboard state: config overrides, admin password hash,
-# installed plugins/themes, and audit logs (default: ./data/admin).
-# For Docker, the default resolves to /app/data/admin - mount a persistent
-# volume there (see docker-compose.yml).
+# Admin data is split across two directories so the config volume can be
+# mounted read-only after the setup wizard completes (see issue #226).
+#
+# Config dir - operator-authored state. Holds config.json, policy.json,
+# admin.json (passwordHash only), plugin-config/, plugins/, themes/, and
+# branding uploads. Safe to mount read-only after setup.
+# Default: ./data/admin (or ADMIN_DATA_DIR if that legacy variable is set)
+# ADMIN_CONFIG_DIR=./data/admin
+#
+# State dir - runtime mutations. Holds admin-state.json (login timestamps),
+# audit.log, and the bootstrap setup token. Always read-write.
+# Default: ./data/admin-state (or ADMIN_DATA_DIR/state when ADMIN_DATA_DIR
+#          is set, for back-compat with single-volume installs)
+# ADMIN_STATE_DIR=./data/admin-state
+#
+# Set to "true" to enforce read-only mode at the application layer (cleaner
+# error than a mid-request EROFS). Pair with `:ro` on the config-volume mount.
+# ADMIN_CONFIG_READONLY=true
+#
+# Legacy: a single dir containing both config and state. Honoured if neither
+# of the split variables is set. New installs should use the split vars.
 # ADMIN_DATA_DIR=./data/admin
 
 # =============================================================================