feat: Add OpenClaw as conversion target

Add openclaw as the 8th conversion target, enabling:
  bunx @every-env/compound-plugin install compound-engineering --to openclaw

Converts Claude Code plugins into OpenClaw's extension format:
- Agents → skills/agent-*/SKILL.md
- Commands → api.registerCommand() + skills/cmd-*/SKILL.md
- Skills → copied verbatim with path rewriting (.claude/ → .openclaw/)
- MCP servers → openclaw.json config
- Generates openclaw.plugin.json manifest, package.json, and index.ts entry point

Output installs to ~/.openclaw/extensions/<plugin-name>/

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

src/types/openclaw.ts

@@ -0,0 +1,52 @@
+export type OpenClawPluginManifest = {
+  id: string
+  name: string
+  kind: "tool"
+  configSchema?: {
+    type: "object"
+    additionalProperties: boolean
+    properties: Record<string, OpenClawConfigProperty>
+    required?: string[]
+  }
+  uiHints?: Record<string, OpenClawUiHint>
+  skills?: string[]
+}
+
+export type OpenClawConfigProperty = {
+  type: string
+  description?: string
+  default?: unknown
+}
+
+export type OpenClawUiHint = {
+  label: string
+  sensitive?: boolean
+  placeholder?: string
+}
+
+export type OpenClawSkillFile = {
+  name: string
+  content: string
+  /** Subdirectory path inside skills/ (e.g. "agent-native-reviewer") */
+  dir: string
+}
+
+export type OpenClawCommandRegistration = {
+  name: string
+  description: string
+  acceptsArgs: boolean
+  /** The prompt body that becomes the command handler response */
+  body: string
+}
+
+export type OpenClawBundle = {
+  manifest: OpenClawPluginManifest
+  packageJson: Record<string, unknown>
+  entryPoint: string
+  skills: OpenClawSkillFile[]
+  /** Skill directories to copy verbatim (original Claude skills with references/) */
+  skillDirCopies: { sourceDir: string; name: string }[]
+  commands: OpenClawCommandRegistration[]
+  /** openclaw.json fragment for MCP servers */
+  openclawConfig?: Record<string, unknown>
+}