feat: serve plugin http and websockets from one mount instead of ports

plugins/ai/src/backend/index.ts

@@ -3,7 +3,7 @@ import { startAiService, stopAiService } from "./routes.js";
 import { createCurrentAiRepository } from "../../../../src/backend/database/repositories/factory.js";
 
 export async function activate(ctx: PluginContext) {
-  startAiService();
+  startAiService(ctx.http.router());
 
   // Offered by reference, not copied: this hands over a resolver, so the key
   // stays ours. Rotating or deleting the provider takes effect on the next
@@ -24,7 +24,7 @@ export async function activate(ctx: PluginContext) {
     return withSecret?.apiKey ?? null;
   });
 
-  ctx.log.info("AI assistant router registered at /ai");
+  ctx.log.info("AI assistant routes mounted at /plugin-api/ai");
 }
 
 export async function deactivate() {

plugins/ai/src/backend/routes.ts

@@ -1,9 +1,5 @@
 import { getErrorMessage } from "../../../../src/backend/utils/error-message.js";
-import express from "express";
-import {
-  registerAiRouter,
-  unregisterAiRouter,
-} from "../../../../src/backend/database/routes/ai-dispatch.js";
+import express, { type Router } from "express";
 import type { AuthenticatedRequest } from "../../../../src/types/index.js";
 import { PermissionManager } from "../../../../src/backend/utils/permission-manager.js";
 import { AuthManager } from "../../../../src/backend/utils/auth-manager.js";
@@ -1339,12 +1335,12 @@ router.post(
   },
 );
 
-/** Called from activate(). Mounts this router at /ai via the shared dispatcher. */
-export function startAiService(): void {
-  registerAiRouter(router);
+/** Called from activate(). Mounts this router at /plugin-api/ai. */
+export function startAiService(mountOn: Router): void {
+  mountOn.use(router);
 }
 
 /** Called from deactivate(). /ai/* falls back to 404 until reactivated. */
 export function stopAiService(): void {
-  unregisterAiRouter();
+  // Unmounted by the runtime when the plugin deactivates.
 }