refactor(channels): make built-in channels self-contained (#4908)

* refactor(channels): own setup and instance contracts

* refactor(channels): isolate management contracts

* refactor(channels): normalize activation contracts

* fix(channels): enforce management contracts

* refactor(channels): finish setup ownership migration

* fix(channels): harden management contracts

* fix(channels): enforce lazy loading and runtime ownership

* fix(feishu): make multi-instance startup idempotent

* fix(webui): render channel setup contracts cleanly

* fix(feishu): stop websocket clients cleanly

* fix(channels): enforce persistence and activation gates

* fix(channels): preserve global feature action scope

* fix(channels): apply defaults for single plugins

* fix(channels): enforce management contract boundaries

* refactor(feishu): remove identity helper indirection

* fix(channels): preserve management setup contracts

* refactor(channels): generalize instance settings UI

* refactor(channels): package channel plugins with web UI metadata

* refactor(channels): make built-ins self-contained packages

* test(channels): colocate tests with channel packages

* fix(dingtalk): use official brand icon

* feat(channels): colocate webui translations

* docs(channels): clarify plugin ownership

* test(exec): remove output wait race

* refactor(channels): unify plugin descriptors

* fix(channels): enforce descriptor-owned contracts

* refactor(channels): finish package-owned plugin setup

* refactor(channels): use repository-owned packages only

* fix(channels): self-describe dependencies and runtime state

* fix(channels): warn about legacy entry points

webui/src/lib/api.ts

@@ -497,9 +497,9 @@ export async function runPairingAction(
 
 export async function startChannelConnect(
   token: string,
-  channel: "feishu" | "weixin",
+  channel: string,
   options: {
-    domain?: "feishu" | "lark";
+    domain?: string;
     instanceId?: string;
     mode?: "replace" | "create";
     force?: boolean;
@@ -520,7 +520,7 @@ export async function startChannelConnect(
 
 export async function pollChannelConnect(
   token: string,
-  channel: "feishu" | "weixin",
+  channel: string,
   sessionId: string,
   base: string = "",
 ): Promise<ChannelConnectPayload> {
@@ -534,7 +534,7 @@ export async function pollChannelConnect(
 
 export async function cancelChannelConnect(
   token: string,
-  channel: "feishu" | "weixin",
+  channel: string,
   sessionId: string,
   base: string = "",
 ): Promise<ChannelConnectPayload> {