feat: vault-aligned server v1 + UX polish

Redesign the optional FastAPI companion around vault files (manifest /
PUT/GET/DELETE + OCR jobs) instead of legacy strokes_json notes. Wire a
client Server settings panel for health/login. Polish shell UX: l10n for
settings/home/board, sticky-board empty state, and a narrow-screen
diagnostics FAB.

Co-authored-by: Cursor <cursoragent@cursor.com>

lib/l10n/app_localizations_zh.dart

@@ -484,4 +484,100 @@ class AppLocalizationsZh extends AppLocalizations {
 
   @override
   String get syncNotConfigured => '请输入服务器地址以启用同步。';
+
+  @override
+  String get settingsDefaults => '默认笔迹';
+
+  @override
+  String get settingsAppearance => '外观';
+
+  @override
+  String get settingsAbout => '关于';
+
+  @override
+  String get settingsDefaultTool => '默认工具';
+
+  @override
+  String get settingsDefaultColor => '默认颜色';
+
+  @override
+  String get settingsDefaultWidth => '默认线宽';
+
+  @override
+  String get settingsPressureCurve => '压感曲线';
+
+  @override
+  String get settingsClearConfirmBody => '将重置笔默认值与外观设置。笔记和文档不会受影响。';
+
+  @override
+  String get serverSection => 'BadNote 服务器';
+
+  @override
+  String get serverUrl => '服务器地址';
+
+  @override
+  String get serverUrlHint => 'http://192.168.1.10:8080';
+
+  @override
+  String get serverUsername => '用户名';
+
+  @override
+  String get serverPassword => '密码';
+
+  @override
+  String get serverSave => '保存并登录';
+
+  @override
+  String get serverTest => '测试连接';
+
+  @override
+  String serverTestOk(String version) {
+    return '连接成功 · API $version';
+  }
+
+  @override
+  String serverTestFail(String error) {
+    return '连接失败：$error';
+  }
+
+  @override
+  String get serverLoggedIn => '已登录';
+
+  @override
+  String get serverHint => '可选。用于自托管 vault 协助同步与延迟 OCR；日常笔记仍完全离线。';
+
+  @override
+  String get boardEmptyTitle => '还没有便利贴';
+
+  @override
+  String get boardEmptyBody => '点按右下角添加卡片。在正文写 [[另一张卡片id]] 可建立双链。';
+
+  @override
+  String get relativeJustNow => '刚刚';
+
+  @override
+  String relativeMinutesAgo(int n) {
+    return '$n 分钟前';
+  }
+
+  @override
+  String relativeHoursAgo(int n) {
+    return '$n 小时前';
+  }
+
+  @override
+  String get relativeYesterday => '昨天';
+
+  @override
+  String diagExported(int bytes) {
+    return '诊断包已导出（$bytes 字节）\n路径已复制';
+  }
+
+  @override
+  String diagExportFail(String error) {
+    return '导出失败：$error';
+  }
+
+  @override
+  String get processingOcr => '正在识别文字…';
 }