feat: Add Qwen Code support

- Add Qwen Code target for converting Claude Code plugins
- Implement claude-to-qwen converter with agent/command/skill mapping
- Write qwen-extension.json config with MCP servers and settings
- Generate QWEN.md context file with plugin documentation
- Support nested commands with colon separator (workflows:plan)
- Extract MCP environment placeholders as settings
- Add --to qwen and --qwen-home CLI options
- Document Qwen installation in README

Co-authored-by: Qwen-Coder <qwen-coder@alibabacloud.com>

src/types/qwen.ts

@@ -0,0 +1,48 @@
+export type QwenExtensionConfig = {
+  name: string
+  version: string
+  mcpServers?: Record<string, QwenMcpServer>
+  contextFileName?: string
+  commands?: string
+  skills?: string
+  agents?: string
+  settings?: QwenSetting[]
+}
+
+export type QwenMcpServer = {
+  command?: string
+  args?: string[]
+  env?: Record<string, string>
+  cwd?: string
+}
+
+export type QwenSetting = {
+  name: string
+  description: string
+  envVar: string
+  sensitive?: boolean
+}
+
+export type QwenAgentFile = {
+  name: string
+  content: string
+  format: "yaml" | "markdown"
+}
+
+export type QwenSkillDir = {
+  sourceDir: string
+  name: string
+}
+
+export type QwenCommandFile = {
+  name: string
+  content: string
+}
+
+export type QwenBundle = {
+  config: QwenExtensionConfig
+  agents: QwenAgentFile[]
+  commandFiles: QwenCommandFile[]
+  skillDirs: QwenSkillDir[]
+  contextFile?: string
+}