Keep a list row's fill under its state layer

Plan step 36 review of 9ff5a7a8. The rewrite dropped the unlayered
selected rule into material.components beside the segmented fill and the
row tint, so on equal or greater weight a selected item in a segmented
list drew surface instead of secondary-container, and hovering, pressing
or focusing any selected row (or a table's selected row) swapped its
fill for a translucent tint. Each fill now names itself
--md-list-row-fill, and the row's layer is its ink mixed over that fill
at the state tokens, which is also C-08's second suggested fix.

A disabled item inks the whole row at the disabled-content token, as the
old root colour did, so the check, the leading slot and the end slot dim
with the text; the three-line padding is a literal 12px like alert.css;
list-rows.js named list.css.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01Qwx5USif3wFFmxtHg5U1g9

resources/css/components/table.css

@@ -9,7 +9,8 @@
  * never a fraction of it, since M3 reserves opacity for state layers and disabled. A selected row
  * (`aria-selected="true"`) is secondary-container. A row that opens something is `data-md-list-row`
  * and answers a pointer as a list row does (components/list-item.css, shared with `<x-card>` and
- * `<x-list-item>`).
+ * `<x-list-item>`); a selected one names its fill `--md-list-row-fill`, so that state layer is laid
+ * over the secondary-container rather than in place of it.
  *
  * A row is 52px: 16px above and below a body-medium line, 12px beside each cell. Density is never
  * applied by itself — "don't apply density by default; offer an explicit density opt-in instead,
@@ -84,7 +85,9 @@
     }
 
     [data-md-table] :where(tbody tr[aria-selected='true']) {
-        background-color: var(--md-sys-color-secondary-container);
+        --md-list-row-fill: var(--md-sys-color-secondary-container);
+
+        background-color: var(--md-list-row-fill);
         color: var(--md-sys-color-on-secondary-container);
     }
 }