Remove unused --ks-rule-strong token

After the border audit reassigned every usage to --ks-kinpaku or
--ks-rule, the muddy gold token is dead. Delete its dark and light
definitions and update the comments that described it.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

site/styles/home-kinpaku.css

@@ -6,8 +6,8 @@
 @import "./kinpaku-tokens.css";
 
 .home-kinpaku {
-  /* --ks-rule / --ks-rule-strong inherit the global tokens (neutral default,
-     gold strong); the homepage no longer diverges on border color. */
+  /* --ks-rule inherits the global token (neutral hairline); the homepage no
+     longer diverges on border color. */
 
   /* Legacy alias — homepage code reads --ks-muted; map it to the global muted
      text token (no divergent value). */

site/styles/kinpaku-tokens.css

@@ -59,13 +59,11 @@
 	--ks-text-mute-deep: oklch(52% 0 0);         /* disabled */
 
 	/* ============================================================
-	   Rules. The default hairline is neutral so borders/dividers/labels
-	   don't carry warmth (warmth lives in the gold accents and surfaces).
-	   "strong" stays gold — it appears on focus, active state, and
-	   structural brand anchors where the gold is the signal.
+	   Rules. The hairline is neutral so borders/dividers/labels don't
+	   carry warmth (warmth lives in the gold accents and surfaces). For a
+	   gold accent border, use --ks-kinpaku directly, not a muddy variant.
 	   ============================================================ */
 	--ks-rule:           oklch(78% 0 0 / 0.16);
-	--ks-rule-strong:    oklch(74% 0.09 82 / 0.6);
 
 	/* ============================================================
 	   Code. One treatment site-wide. Inline code is a neutral graphite
@@ -197,7 +195,6 @@ html.light {
 
 	/* Rules — dark hairlines. */
 	--ks-rule:           oklch(25% 0.02 95 / 0.12);
-	--ks-rule-strong:    oklch(61% 0.085 78 / 0.45);
 
 	/* Code — light chips, dark text. */
 	--ks-code-fg:         oklch(28% 0.02 95);

site/styles/light-mode.css

@@ -62,9 +62,8 @@ html.light .theme-toggle .theme-toggle-icon--dark {
 }
 
 /* Light mode: the toggle and the GitHub pill both read as refined hairline
-   chips — neutral hairline (--ks-rule, not the gold --ks-rule-strong), no fill.
-   The contextual seam scrim (below) carries them over the bright hero corner,
-   so neither needs a solid backing of its own. */
+   chips — neutral --ks-rule border, no fill. The contextual seam scrim (below)
+   carries them over the bright hero corner, so neither needs a solid backing. */
 html.light .kinpaku-chrome .theme-toggle {
   border-color: var(--ks-rule);
   color: var(--ks-text-muted);