Add custom headers to direct connections (#2922)

* Add custom headers to direct connections

* Address custom header review feedback

* Fix direct connection header integration

* Fix desktop relay E2E transport setup

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Co-authored-by: Claude <claude@Claudes-Mac-mini.local>
Co-authored-by: Mohamed Boudra <boudra.moha@gmail.com>

packages/protocol/src/host-connection-schema.ts

@@ -6,6 +6,7 @@ export const DirectTcpHostConnectionSchema = z.object({
   endpoint: z.string(),
   useTls: z.boolean().optional().default(false),
   password: z.string().optional(),
+  headers: z.record(z.string(), z.string()).optional(),
 });
 
 export type DirectTcpHostConnection = z.input<typeof DirectTcpHostConnectionSchema>;