feat: channel plugin architecture with decoupled configs

- Add plugin discovery via Python entry_points (group: nanobot.channels)
- Move 11 channel Config classes from schema.py into their own channel modules
- ChannelsConfig now only keeps send_progress + send_tool_hints (extra=allow)
- Each built-in channel parses dict->Pydantic in __init__, zero internal changes
- All channels implement default_config() for onboard auto-population
- nanobot onboard injects defaults for all discovered channels (built-in + plugins)
- Add nanobot plugins list CLI command
- Add Channel Plugin Guide (docs/CHANNEL_PLUGIN_GUIDE.md)
- Fully backward compatible: existing config.json and sessions work as-is
- 340 tests pass, zero regressions

nanobot/channels/mochat.py

@@ -16,7 +16,8 @@ from nanobot.bus.events import OutboundMessage
 from nanobot.bus.queue import MessageBus
 from nanobot.channels.base import BaseChannel
 from nanobot.config.paths import get_runtime_subdir
-from nanobot.config.schema import MochatConfig
+from nanobot.config.schema import Base
+from pydantic import Field
 
 try:
     import socketio
@@ -208,6 +209,49 @@ def parse_timestamp(value: Any) -> int | None:
         return None
 
 
+# ---------------------------------------------------------------------------
+# Config classes
+# ---------------------------------------------------------------------------
+
+class MochatMentionConfig(Base):
+    """Mochat mention behavior configuration."""
+
+    require_in_groups: bool = False
+
+
+class MochatGroupRule(Base):
+    """Mochat per-group mention requirement."""
+
+    require_mention: bool = False
+
+
+class MochatConfig(Base):
+    """Mochat channel configuration."""
+
+    enabled: bool = False
+    base_url: str = "https://mochat.io"
+    socket_url: str = ""
+    socket_path: str = "/socket.io"
+    socket_disable_msgpack: bool = False
+    socket_reconnect_delay_ms: int = 1000
+    socket_max_reconnect_delay_ms: int = 10000
+    socket_connect_timeout_ms: int = 10000
+    refresh_interval_ms: int = 30000
+    watch_timeout_ms: int = 25000
+    watch_limit: int = 100
+    retry_delay_ms: int = 500
+    max_retry_attempts: int = 0
+    claw_token: str = ""
+    agent_user_id: str = ""
+    sessions: list[str] = Field(default_factory=list)
+    panels: list[str] = Field(default_factory=list)
+    allow_from: list[str] = Field(default_factory=list)
+    mention: MochatMentionConfig = Field(default_factory=MochatMentionConfig)
+    groups: dict[str, MochatGroupRule] = Field(default_factory=dict)
+    reply_delay_mode: str = "non-mention"
+    reply_delay_ms: int = 120000
+
+
 # ---------------------------------------------------------------------------
 # Channel
 # ---------------------------------------------------------------------------
@@ -218,7 +262,13 @@ class MochatChannel(BaseChannel):
     name = "mochat"
     display_name = "Mochat"
 
-    def __init__(self, config: MochatConfig, bus: MessageBus):
+    @classmethod
+    def default_config(cls) -> dict[str, Any]:
+        return MochatConfig().model_dump(by_alias=True)
+
+    def __init__(self, config: Any, bus: MessageBus):
+        if isinstance(config, dict):
+            config = MochatConfig.model_validate(config)
         super().__init__(config, bus)
         self.config: MochatConfig = config
         self._http: httpx.AsyncClient | None = None