fix(rust-bridge): correct Email.addHeader() calls and IBounceDetection interface

Use addHeader() instead of non-existent setHeader() for security
result headers, and align IBounceDetection with actual Rust struct
fields (bounce_type + category only).

dist_ts/mail/routing/classes.unified.email.server.d.ts

@@ -134,6 +134,7 @@ export declare class UnifiedEmailServer extends EventEmitter {
     private servers;
     private stats;
     dkimCreator: DKIMCreator;
+    private rustBridge;
     private ipReputationChecker;
     private bounceManager;
     private ipWarmupManager;
@@ -163,6 +164,11 @@ export declare class UnifiedEmailServer extends EventEmitter {
      * Stop the unified email server
      */
     stop(): Promise<void>;
+    /**
+     * Verify inbound email security (DKIM/SPF/DMARC) using the Rust bridge.
+     * Falls back gracefully if the bridge is not running.
+     */
+    private verifyInboundSecurity;
     /**
      * Process email based on routing rules
      */