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>

plugins/jsc-mod-companion/hooks/companion/engine-fs.ts

@@ -0,0 +1,26 @@
+import type { Fs } from './fs'
+
+// hooks 沙箱沒有 node:fs，改用引擎的 $.fs；它沒有 rename，所以不提供（writeAtomic 會直接覆寫）
+type EngineFs = {
+  read(path: string): Promise<string>
+  write(path: string, text: string): Promise<void>
+  list(path?: string): Promise<{ name: string }[]>
+}
+
+export const engineFs = (fs: EngineFs): Fs => ({
+  async read(path) {
+    try {
+      return await fs.read(path)
+    } catch {
+      return null
+    }
+  },
+  write: (path, data) => fs.write(path, data),
+  async list(dir) {
+    try {
+      return (await fs.list(dir)).map(e => e.name).filter(n => !n.endsWith('.tmp')).sort()
+    } catch {
+      return []
+    }
+  },
+})