complete oklch migration: zero named palette refs remain

- 01-asw.css: 20 new tokens (14 --syntax-*, 6 utility: print, absolute, high-contrast)
- Layers 02-09: all 30 TODO refs replaced with semantic/syntax tokens
- Zero --gray-N, --green-N, --blue-N, --red-N, --yellow-N in layers 02-09
- Palette-hue knob now controls entire site. Syntax highlighting uses fixed oklch hues.

assets/css/layers/04-data-attrs.css

@@ -398,12 +398,12 @@
 
 [data-diff-line="added"] {
   background: var(--diff-add-bg);
-  color: var(--green-3); /* TODO: map to semantic token — no alias for green-3 (--accent-hover=green-4 is one step darker) */
+  color: var(--syntax-string);
 }
 
 [data-diff-line="added"]::before {
   content: "+";
-  color: var(--ok);  /* --ok = var(--green-5) */
+  color: var(--ok);
 }
 
 [data-diff-line="removed"] {
@@ -413,7 +413,7 @@
 
 [data-diff-line="removed"]::before {
   content: "−";
-  color: var(--red-6); /* TODO: map to semantic token — no alias for red-6 (--error=red-7, --callout-error=red-5) */
+  color: var(--syntax-deleted);
 }
 
 [data-diff-line="context"] {
@@ -497,12 +497,12 @@
 /* Light mode adjustments */
 @media (prefers-color-scheme: light) {
   [data-redacted] {
-    background: var(--gray-15); /* TODO: map to semantic token — no alias for absolute black; needed for redaction bar in light mode */
+    background: var(--absolute-black);
   }
   [data-redacted="reveal"]:hover,
   [data-redacted="reveal"]:focus {
-    background: var(--surface-1);  /* light mode: --surface-1 = var(--gray-1) */
-    color: var(--gray-15); /* TODO: map to semantic token — no alias for absolute black text in light mode */
+    background: var(--surface-1);
+    color: var(--absolute-black);
   }
 }