refactor: jsc-mod 改名 jsc-mod-statusline、jsc-companion 改名 jsc-mod-companion,指令拆成獨立指令

- jsc-mod-statusline:/jsc-mod-statusline:enable、compact、disable
- jsc-mod-companion:/jsc-mod-companion:status、switch、disable、setup、todo、quiet
- 同步更新 plugin.json、marketplace.json 與各 README
- 補上 statusline band 測試缺少的 ui.render 底層處理

Co-Authored-By: Claude Sonnet 5.5 <noreply@anthropic.com>

.claude-plugin/marketplace.json

@@ -6,13 +6,13 @@
   },
   "plugins": [
     {
-      "name": "jsc-mod",
-      "source": "./plugins/jsc-mod",
+      "name": "jsc-mod-statusline",
+      "source": "./plugins/jsc-mod-statusline",
       "description": "輸入框上方單行狀態列：模型、目錄、分支、5h/7d 額度與重置、context、CPU/記憶體/磁碟"
     },
     {
-      "name": "jsc-companion",
-      "source": "./plugins/jsc-companion",
+      "name": "jsc-mod-companion",
+      "source": "./plugins/jsc-mod-companion",
       "description": "小說角色陪伴：人設注入、語氣、心情與好感、互動記憶、主動關心與待辦，並可用 ingest skill 解析小說建立角色"
     },
     {