feat: skill 随插件自动注册，免去 extra_skill_dirs 配置

kimi.plugin.json 声明 skills:["./skills"]，/plugins install 后 /skill kimi-eyes 经 PluginSkillSource 自动注册（源码 manifest.ts:100 + pluginSkillRoots 全链路证实）；package.json files 补 skills/；README（中英）与网页把「两步配置」简化为「一步」（只声明 image_in）。1.0.7 → 1.0.8。

kimi.plugin.json

@@ -1,6 +1,6 @@
 {
   "name": "kimi-eyes",
-  "version": "1.0.7",
+  "version": "1.0.8",
   "description": "Give non-multimodal models vision: analyze local images and clipboard screenshots through a user-configured VLM API (OpenAI-compatible or Anthropic protocol).",
   "keywords": [
     "vision",
@@ -17,6 +17,9 @@
     "longDescription": "读取本地图片或剪贴板截图，调用用户自配的多模态 API（OpenAI 兼容或 Anthropic 协议）返回描述。多模态模型不受影响，粘贴即原生看图。"
   },
   "systemPromptPath": "./SYSTEM.md",
+  "skills": [
+    "./skills"
+  ],
   "mcpServers": {
     "kimi-eyes": {
       "command": "node",