feat(sdk): 插件 SDK（Tool/Skill/Channel 接口 + 注册辅助 + 配置 hook）

pkg/plugins/sdk/channel.go

@@ -0,0 +1,29 @@
+package sdk
+
+import "context"
+
+// Channel registers a chat platform adapter (QQ, WeChat, Telegram, ...).
+//
+// The SDK pins only the lifecycle shape. The authoritative contract for
+// adapters lives in internal/channel/adapter (design authority
+// DevDocs/design/08-渠道接入.md §1, the PlatformAdapter contract) and is
+// implemented in milestone M6. This interface mirrors the lifecycle portion of
+// that contract — Name/Connect/Disconnect/IsConnected/HealthCheck — without
+// depending on the internal message model, so a platform plugin can register
+// itself here while the message flow is provided by the channel layer.
+//
+// Implementations must be safe for concurrent use.
+type Channel interface {
+	// Name returns the platform identifier (for example "qq", "telegram").
+	Name() string
+	// Connect establishes the platform connection using config. It may be
+	// called more than once and must be idempotent.
+	Connect(ctx context.Context, config any) error
+	// Disconnect tears the connection down gracefully. It returns nil when the
+	// adapter was already disconnected.
+	Disconnect(ctx context.Context) error
+	// IsConnected reports whether the connection is currently up.
+	IsConnected() bool
+	// HealthCheck probes the platform and returns an error when it is unhealthy.
+	HealthCheck(ctx context.Context) error
+}