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

pkg/plugins/sdk/skill.go

@@ -0,0 +1,55 @@
+package sdk
+
+// Step is one unit of a Skill's reusable workflow.
+type Step struct {
+	// Name is a short identifier for the step.
+	Name string
+	// Prompt is the instruction the model follows for this step.
+	Prompt string
+	// Depends lists the Names of steps that must finish before this step runs.
+	Depends []string
+}
+
+// Ref is a reference a Skill may pull in for extra context or shared tooling.
+type Ref struct {
+	// Name identifies the reference.
+	Name string
+	// Type is a free-form kind, for example "tool", "doc" or "file".
+	Type string
+	// Value is the reference payload or pointer.
+	Value string
+	// Optional reports whether the reference may be absent without failing.
+	Optional bool
+}
+
+// Guardrail is a constraint a Skill applies while running.
+type Guardrail struct {
+	// ID names the guardrail.
+	ID string
+	// Message is the rule text enforced on the workflow.
+	Message string
+	// Enforced reports whether a violation aborts the Skill (true) or is only a
+	// warning (false).
+	Enforced bool
+}
+
+// Skill is a reusable, higher-order workflow: an ordered set of steps paired
+// with prompts, references and guardrails. It is more structured than a Tool
+// and typically composes several steps.
+//
+// Implementations must be safe for concurrent use.
+type Skill interface {
+	// Name returns the unique skill identifier.
+	Name() string
+	// Description explains what the Skill accomplishes; the model uses it to
+	// select a Skill for a task.
+	Description() string
+	// Prompt returns the base system prompt for the Skill.
+	Prompt() string
+	// Steps returns the ordered workflow steps.
+	Steps() []Step
+	// Refs returns the references the Skill may draw on.
+	Refs() []Ref
+	// Guardrails returns the constraints the Skill enforces.
+	Guardrails() []Guardrail
+}