feat(ui): warm light theme and pre-mixed status fills

- Light mode moves to Claude's ivory/terracotta family: page #e8e5da, cards
  #f5f3ec (a notch below Claude's ivory, no pure-white step), warm
  borders and card shadow; dark mode is untouched.
- The surface ramp rises in lightness with its index in BOTH themes, so a
  card sits brighter than the page and every hover lifts instead of dims.
- Light --accent #a34a28 (the brand #cc785c is 3.1:1 on ivory); --fg-muted
  held at >=4.5:1; new --syn-* syntax tokens, dark keeps its pastels.
- Status/accent fills (bg-*/N, border-*/N) compile to color-mix against
  --tint-base instead of rgb(/a), so a chip is one colour on every surface.
- Hardcoded dark-only hovers (hover:text-white, hover:bg-white/5) replaced
  by tokens in DateTimePicker and SessionDrillIn.

client/src/lib/highlight.ts

@@ -1033,46 +1033,49 @@ export function highlight(source: string, lang: string): Token[] {
 /**
  * Map a token type to a Tailwind colour class for rendering.
  * @param type A {@link TokenType} produced by {@link highlight}.
- * @returns Tailwind utility classes (text colour, and a background tint for
- *   diff add/remove lines); falls back to a neutral gray for "plain"/unknown.
+ * @returns Tailwind utility classes built on the `syntax.*` THEME TOKENS
+ *   (`--syn-*` in index.css), not on fixed palette steps: the dark set is the
+ *   pastel one this file has always used, and light mode takes the same hues
+ *   four steps darker, because a pastel keyword on a light code block is
+ *   unreadable. Diff rows keep their faint ±10% tint, which works on both.
  */
 export function tokenClass(type: TokenType): string {
   switch (type) {
     case "comment":
-      return "text-gray-500 italic"; // muted + italic to recede visually
+      return "text-syntax-comment italic"; // muted + italic to recede visually
     case "string":
-      return "text-emerald-300"; // green, shared with diff-add text
+      return "text-syntax-string"; // green, shared with diff-add text
     case "number":
-      return "text-orange-300"; // orange, shared with boolean literals
+      return "text-syntax-number"; // orange, shared with boolean literals
     case "keyword":
-      return "text-violet-300"; // violet, shared with diff-meta headers
+      return "text-syntax-keyword"; // violet, shared with diff-meta headers
     case "builtin":
-      return "text-sky-300";
+      return "text-syntax-builtin";
     case "function":
-      return "text-yellow-200"; // yellow, shared with HTML attr names
+      return "text-syntax-function"; // yellow, shared with HTML attr names
     case "operator":
-      return "text-pink-300";
+      return "text-syntax-operator";
     case "punctuation":
-      return "text-gray-400"; // slightly brighter than comments, dimmer than plain
+      return "text-syntax-punctuation"; // brighter than comments, dimmer than plain
     case "property":
-      return "text-cyan-300";
+      return "text-syntax-property";
     case "tag":
-      return "text-rose-300";
+      return "text-syntax-tag";
     case "attr":
-      return "text-yellow-200"; // matches "function" colour by design
+      return "text-syntax-function"; // matches "function" colour by design
     case "variable":
-      return "text-amber-300";
+      return "text-syntax-function"; // amber family, same as functions/attrs
     case "boolean":
-      return "text-orange-300"; // literals grouped with numbers by colour
+      return "text-syntax-number"; // literals grouped with numbers by colour
     case "diff-add":
-      return "text-emerald-300 bg-emerald-500/10"; // green text + faint green row tint
+      return "text-syntax-add bg-emerald-500/10"; // green text + faint green row tint
     case "diff-del":
-      return "text-red-300 bg-red-500/10"; // red text + faint red row tint
+      return "text-syntax-del bg-red-500/10"; // red text + faint red row tint
     case "diff-meta":
-      return "text-violet-300";
+      return "text-syntax-keyword";
     case "plain":
     default:
-      return "text-gray-200"; // default body text colour
+      return "text-syntax-plain"; // default body text colour
   }
 }