Fix Stalwart accessibility by adding stalwart.toml ConfigMap

Issue: Stalwart pod was crashing with "expected value at line 1 column 1"
when trying to parse /etc/stalwart/stalwart.toml because the file was not
being mounted.

Root cause: The StatefulSet was only mounting bootstrap-config (config.json)
but Stalwart v0.16.11 expects stalwart.toml for runtime configuration.

Changes:
- Add stalwart-config.yaml ConfigMap with complete stalwart.toml
- Update StatefulSet to mount stalwart-config at /etc/stalwart/stalwart.toml
- Keep bootstrap-config mount for backward compatibility

This resolves DEV-422 (Stalwart not accessible).

Co-Authored-By: Paperclip <noreply@paperclip.ing>

apps/stalwart/stalwart-config.yaml

@@ -0,0 +1,66 @@
+---
+apiVersion: v1
+kind: ConfigMap
+metadata:
+  name: stalwart-config
+  namespace: stalwart
+data:
+  stalwart.toml: |
+    #
+    # Stalwart Mail Server Configuration
+    #
+
+    [store]
+    data = "rocksdb"
+
+    [store.rocksdb]
+    type = "rocksdb"
+    path = "/var/lib/stalwart"
+
+    #
+    # Server Configuration
+    #
+
+    [server]
+    hostname = "mail.basicstack.de"
+
+    # HTTP Listener (Web UI and API)
+    [server.listener.http]
+    bind = ["0.0.0.0:8080"]
+    protocol = "http"
+
+    # Security: Allow internal cluster IPs for Traefik ingress
+    # Pod network CIDR: 10.244.0.0/16
+    [server.listener.http.security]
+    allowed-ips = ["10.244.0.0/16", "127.0.0.1/32"]
+
+    # SMTP Listener (Port 25)
+    [server.listener.smtp]
+    bind = ["0.0.0.0:25"]
+    protocol = "smtp"
+
+    # Submission Listener (Port 587 with STARTTLS)
+    [server.listener.submission]
+    bind = ["0.0.0.0:587"]
+    protocol = "smtp"
+
+    # IMAPS Listener (Port 993 with TLS)
+    [server.listener.imaps]
+    bind = ["0.0.0.0:993"]
+    protocol = "imap"
+    tls.implicit = true
+
+    #
+    # TLS Configuration
+    #
+
+    [server.tls]
+    certificate = "file:///etc/stalwart/certs/tls.crt"
+    private-key = "file:///etc/stalwart/certs/tls.key"
+
+    #
+    # Logging
+    #
+
+    [tracing.level]
+    default = "info"

apps/stalwart/stalwart-fresh-deployment.yaml

@@ -128,6 +128,9 @@ spec:
         - name: bootstrap-config
           mountPath: /etc/stalwart/config.json
           subPath: config.json
+        - name: stalwart-config
+          mountPath: /etc/stalwart/stalwart.toml
+          subPath: stalwart.toml
         - name: tls-certs
           mountPath: /etc/stalwart/certs
           readOnly: true
@@ -181,6 +184,9 @@ spec:
       - name: bootstrap-config
         configMap:
           name: stalwart-bootstrap-config
+      - name: stalwart-config
+        configMap:
+          name: stalwart-config
       - name: tls-certs
         secret:
           secretName: stalwart-tls