feat(client): token 地基补字阶/圆角/间距标量层 AppDims（codegen 单源）

gen_tokens.mjs 扩展解析 :root 共享块 → 生成 app_dims.g.dart：
间距 sp1-10 / 圆角 rSm-rPill / 字号 fsDisplay-fsXs，主题无关 const 标量。
为屏幕重建提供「禁硬编码 px」的单一真源；app_tokens.g.dart 保持字节一致。

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01TSKEiHsvauyxYUW2itzUXX

client/lib/core/theme/app_dims.g.dart

@@ -0,0 +1,30 @@
+// GENERATED by tool/gen_tokens.mjs — DO NOT EDIT.
+// 源：lib/core/theme/token_source/tokens.css（:root 共享块，主题无关）。改尺寸请改源后重跑脚本。
+// 间距/圆角/字号三套主题统一，故为 const 标量，不进 per-theme AppTokens。
+
+class AppDims {
+  AppDims._();
+  // 间距
+  static const double sp1 = 4;
+  static const double sp2 = 8;
+  static const double sp3 = 12;
+  static const double sp4 = 16;
+  static const double sp5 = 20;
+  static const double sp6 = 24;
+  static const double sp8 = 32;
+  static const double sp10 = 40;
+  // 圆角
+  static const double rSm = 4;
+  static const double rMd = 6;
+  static const double rLg = 10;
+  static const double rXl = 14;
+  static const double rPill = 999;
+  // 字号
+  static const double fsDisplay = 28;
+  static const double fsH1 = 21;
+  static const double fsH2 = 17;
+  static const double fsTitle = 15;
+  static const double fsBody = 13;
+  static const double fsSm = 12;
+  static const double fsXs = 11;
+}