M3: dead code purge + layer refs → semantic tokens

Dead code removed:
- 05-utilities: grid-2/card-grid/stats block (superseded by 08-layout)
- 02-semantic: dialog min-width:100% (conflicted with 03-components)
- 02-semantic: hgroup p dead font-family, redundant nested list margin
- All layers: [ai-disclosure] → [data-ai-disclosure] (bug fix)
- table.striped → [data-table="striped"] (classless alignment)

Ref cleanup: 12 --gray-N/--green-N/--blue-N replaced with semantic
tokens. 24 refs marked TODO (syntax highlighting needs --syntax-* aliases).

assets/css/layers/02-semantic.css

@@ -84,9 +84,7 @@ figcaption,
 button,
 input,
 select,
-textarea,
-hgroup > p,
-hgroup > small {
+textarea {
   font-family: var(--font-ui);
 }
 
@@ -169,7 +167,6 @@ ul {
 
 /* Nested lists: reduce spacing */
 :where(dl, ol, ul) :where(dl, ol, ul) {
-  margin: 0;
   margin-top: calc(var(--type-space) * 0.25);
 }
 
@@ -326,8 +323,8 @@ tfoot td {
 }
 
 /* Striped tables (class-based but useful) */
-table.striped tbody tr:nth-child(odd) th,
-table.striped tbody tr:nth-child(odd) td {
+[data-table="striped"] tbody tr:nth-child(odd) th,
+[data-table="striped"] tbody tr:nth-child(odd) td {
   background-color: var(--table-stripe);
 }
 
@@ -410,7 +407,7 @@ pre[class*="language-"] {
 .token.prolog,
 .token.doctype,
 .token.cdata {
-  color: var(--gray-6);       /* muted: ~55% lightness */
+  color: var(--gray-6); /* TODO: map to semantic token — no alias for gray-6 (between --text-3: gray-5 and --text-dim: gray-7) */
   font-style: italic;
 }
 
@@ -420,19 +417,19 @@ pre[class*="language-"] {
 
 .token.tag,
 .token.deleted {
-  color: var(--red-4);        /* HTML tags, deleted code */
+  color: var(--red-4); /* TODO: map to semantic token — no alias for red-4 (--error=red-7, --callout-error=red-5; syntax highlight needs lighter shade) */
 }
 
 .token.attr-name,
 .token.namespace {
-  color: var(--yellow-4);     /* attribute names */
+  color: var(--yellow-4); /* TODO: map to semantic token — no alias for yellow-4 (--warn=yellow-5 is close but one step darker) */
 }
 
 .token.string,
 .token.attr-value,
 .token.char,
 .token.inserted {
-  color: var(--green-4);      /* strings, values */
+  color: var(--accent-hover);  /* strings, values — --accent-hover = var(--green-4) */
 }
 
 .token.number,
@@ -449,7 +446,7 @@ pre[class*="language-"] {
 
 .token.keyword,
 .token.atrule {
-  color: var(--blue-4);       /* keywords, @rules */
+  color: var(--link-hover);    /* keywords, @rules — --link-hover = var(--blue-4) */
 }
 
 .token.function,
@@ -458,7 +455,7 @@ pre[class*="language-"] {
 }
 
 .token.property {
-  color: var(--blue-5);       /* object properties */
+  color: var(--info);          /* object properties — --info = var(--blue-5) */
 }
 
 .token.operator,
@@ -473,7 +470,7 @@ pre[class*="language-"] {
 
 .token.important,
 .token.variable {
-  color: var(--yellow-5);     /* !important, variables */
+  color: var(--warn);          /* !important, variables — --warn = var(--yellow-5) */
   font-weight: var(--font-weight-5);
 }
 
@@ -485,20 +482,20 @@ pre[class*="language-"] {
   .token.comment,
   .token.prolog,
   .token.doctype,
-  .token.cdata    { color: var(--gray-6); }
+  .token.cdata    { color: var(--gray-6); /* TODO: map to semantic token — no alias for gray-6 in light mode */ }
 
-  .token.punctuation   { color: var(--gray-8); }
+  .token.punctuation   { color: var(--gray-8); /* TODO: map to semantic token — no alias for gray-8 */ }
 
   .token.tag,
-  .token.deleted       { color: var(--red-8); }
+  .token.deleted       { color: var(--red-8); /* TODO: map to semantic token — no alias for red-8 */ }
 
   .token.attr-name,
-  .token.namespace     { color: var(--yellow-9); }
+  .token.namespace     { color: var(--yellow-9); /* TODO: map to semantic token — no alias for yellow-9 */ }
 
   .token.string,
   .token.attr-value,
   .token.char,
-  .token.inserted      { color: var(--green-8); }
+  .token.inserted      { color: var(--green-8); /* TODO: map to semantic token — no alias for green-8 */ }
 
   .token.number,
   .token.boolean,
@@ -509,21 +506,21 @@ pre[class*="language-"] {
   .token.builtin       { color: var(--teal-8); }
 
   .token.keyword,
-  .token.atrule        { color: var(--blue-8); }
+  .token.atrule        { color: var(--blue-8); /* TODO: map to semantic token — no alias for blue-8 */ }
 
   .token.function,
   .token.class-name    { color: var(--cyan-9); }
 
-  .token.property      { color: var(--blue-9); }
+  .token.property      { color: var(--blue-9); /* TODO: map to semantic token — no alias for blue-9 */ }
 
   .token.operator,
   .token.entity,
-  .token.url           { color: var(--gray-8); }
+  .token.url           { color: var(--gray-8); /* TODO: map to semantic token — no alias for gray-8 in light mode */ }
 
   .token.regex         { color: var(--orange-7); }
 
   .token.important,
-  .token.variable      { color: var(--yellow-9); }
+  .token.variable      { color: var(--yellow-9); /* TODO: map to semantic token — no alias for yellow-9 */ }
 }
 
 /* ── Details / Summary ─────────────────────────────────────────────── */
@@ -603,7 +600,7 @@ dialog {
   align-items: center;
   justify-content: center;
   width: inherit;
-  min-width: 100%;
+  min-width: auto;
   height: inherit;
   min-height: 100%;
   padding: 0;