feat: 全面清除用户/AI可见的 opencode 痕迹

- system.ts 不再把真实 model id 喂给 LLM（修复"底层是opencode/big-pickle"）
- TUI 首页 tips、窗口标题、ACP 弹窗、命令提示文案全部 → zmo
- config schema URL → zmo.dev；配置路径提示 → ~/.config/zmo、.zmo/
- 发给各家 LLM API 的标识头(X-Title/Referer/Source/UA/originator)→ zmo
- 保留：opencode provider 路由id、@opencode-ai 包名、opencode.json/OPENCODE_* 兼容

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

packages/opencode/src/cli/cmd/providers.ts

@@ -301,7 +301,7 @@ export const ProvidersLoginCommand = effectCmd({
   builder: (yargs) =>
     yargs
       .positional("url", {
-        describe: "opencode auth provider",
+        describe: "zmo auth provider",
         type: "string",
       })
       .option("provider", {