feat: add server listen address configuration to .env and README

.env.example

@@ -67,6 +67,17 @@ JMAP_SERVER_URL=https://your-jmap-server.com
 # For Docker, mount a persistent volume at this path.
 # SETTINGS_DATA_DIR=./data/settings
 
+# =============================================================================
+# Server Listen Address
+# =============================================================================
+
+# Hostname the server binds to (default: 0.0.0.0)
+# Set to "::" for IPv6 or "[::]" for dual-stack support.
+# HOSTNAME=0.0.0.0
+
+# Port the server listens on (default: 3000)
+# PORT=3000
+
 # =============================================================================
 # Logging
 # =============================================================================

README.md

@@ -243,6 +243,16 @@ APP_NAME=My Webmail
 
 All variables are **runtime** — Docker deployments can be configured without rebuilding.
 
+<details>
+<summary>Server Listen Address</summary>
+
+```env
+HOSTNAME=0.0.0.0    # Default; use "::" for IPv6
+PORT=3000            # Default listen port
+```
+
+</details>
+
 <details>
 <summary>OAuth2/OIDC (SSO)</summary>
 

docker-compose.yml

@@ -3,6 +3,9 @@ services:
     image: ghcr.io/bulwarkmail/webmail:latest
     ports:
       - "3000:3000"
+    environment:
+      - HOSTNAME=0.0.0.0     # Use "::" for IPv6
+      - PORT=3000
     env_file:
       - .env.local
     healthcheck: