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

tests/cli/test_commands.py

@@ -480,18 +480,25 @@ def test_config_dump_excludes_oauth_provider_blocks():
 
 
 def test_plugins_list_uses_explicit_config(monkeypatch, tmp_path: Path):
+    from nanobot.channels.plugin import ChannelPlugin
+
     config_path = tmp_path / "config.json"
     config_path.write_text(
         json.dumps({"channels": {"example": {"enabled": True}}}),
         encoding="utf-8",
     )
-    monkeypatch.setattr(
-        "nanobot.channels.registry.discover_channel_names",
-        lambda: ["example"],
+    plugin = ChannelPlugin(
+        name="example",
+        display_name="Example",
+        runtime="example.runtime:ExampleChannel",
     )
     monkeypatch.setattr(
         "nanobot.channels.registry.discover_plugins",
-        lambda: {},
+        lambda enabled_names=None: (
+            {"example": plugin}
+            if enabled_names is None or "example" in enabled_names
+            else {}
+        ),
     )
     monkeypatch.setattr(
         "nanobot.optional_features.optional_dependency_groups",