Fix ListView selection and cursor rendering (regressions from Stage 2)

You were right that selecting a line looked off. Three separate problems, two
of them introduced by the Stage 2 dark-mode block:

1. The selection band was ERASED in dark mode. Stage 2 restated the dark
   surface on `table > tbody > tr > *`, i.e. on the CELLS — but 7.css paints
   tr.highlighted on the ROW, and a cell background paints over a row
   background. The selected row kept only its 1px border and no fill. The base
   surface now goes on `table` alone; cells stay transparent so the row band
   shows through. Same trap re-applies to the cell separators, which 7.css
   deliberately drops inside a selected row and the dark rule was re-adding.

2. The cursor rectangle was drawn PER CELL. `tr.is-cursor > *` puts a dotted
   outline around every cell, so the focused row rendered as a row of dotted
   boxes. Win7 drew one rectangle around the row — the outline belongs on the
   `tr`.

3. Selection was barely visible even in light, and that one is 7.css's own
   semantics rather than a bug: listview's `.highlighted` is Win7's *inactive*
   selection, a near-white wash. Win7 drew the FOCUSED pane's selection as the
   stronger Aero band. The table now carries `is-active` from the panel's own
   isActive(), and the focused pane's selection uses --w7-el-grad-h/-bd-h,
   which the dark palette already restates, so it recolours for free.

Verified by cropping and zooming the harness screenshots in both themes rather
than eyeballing a full page: full-row band, separators dropped inside it, and a
single dotted rectangle on the cursor row.

Co-Authored-By: Claude <noreply@anthropic.com>

ui/dev/harness.html

@@ -91,8 +91,8 @@
         </table>
       </figure>
       <figure class="cell" style="margin:0">
-        <figcaption>ours — file-panel.html (selected + cursor row)</figcaption>
+        <figcaption>ours — focused panel (is-active): selected + cursor</figcaption>
-        <table>
+        <table class="is-active">
           <colgroup>
             <col />
             <col style="width: 5.5rem" />

ui/src/app/file-panel/file-panel.html

@@ -242,7 +242,7 @@
        position:sticky, which is why it moved in here), the sorted column is
        .highlighted.indicator[.up], and the selection band is tr.highlighted.
        Widths come from <colgroup> because 7.css sets table-layout:fixed. -->
-  <table>
+  <table [class.is-active]="isActive()">
     <colgroup>
       <col />
       @for (col of visibleColumns(); track col.key) {

ui/src/styles.css

@@ -610,10 +610,13 @@ body {
      white header gradient) instead of --w7-* vars, so unlike the rest of the
      skin it does NOT follow the hand-authored dark palette — the header labels
      came out invisible, dark on dark. These restate the same rules in dark
-     terms; they are scoped to the dark arms only so light keeps 7.css's own
+     terms; light keeps 7.css's own values untouched.
-     values untouched. */
+
-  .win7[data-theme='dark'] table,
+     CRITICAL: the base surface goes on `table`, NEVER on `tbody > tr > *`.
-  .win7[data-theme='dark'] table > tbody > tr > * {
+     7.css paints the selection band on the ROW, and a cell background paints
+     over a row background — setting one erased the selection highlight
+     entirely in dark mode. */
+  .win7[data-theme='dark'] table {
     background-color: var(--w7-el-bg-s-2);
     border-color: var(--w7-el-bd-d);
     color: var(--w7-el-c);
@@ -626,11 +629,30 @@ body {
   .win7[data-theme='dark'] table > tbody > tr > :not(:last-child) {
     border-right-color: var(--w7-el-bd-d);
   }
+  /* 7.css drops the cell separators inside a selected row; the rule above is
+     more specific than its, so restore that behaviour explicitly. */
+  .win7[data-theme='dark'] table > tbody > tr.highlighted > :not(:last-child) {
+    border-right: none;
+  }
+  .win7[data-theme='dark'] table > tbody > tr.highlighted {
+    background: var(--w7-li-bg-hl);
+    border-color: var(--w7-li-bd-hl);
+  }
 
-  /* The keyboard cursor. 7.css models only selection (tr.highlighted); Win7
+  /* Selection in the FOCUSED panel. 7.css's tr.highlighted is Win7's *inactive*
-     drew the focused row with a dotted focus rectangle on top of it, which is
+     selection — a near-white wash that is almost invisible when it is the
-     what distinguishes "cursor" from "selected" when they differ. */
+     panel you are actually working in. Win7 drew the focused pane's selection
-  .win7 table > tbody > tr.is-cursor > * {
+     as the stronger Aero band, which is what --w7-el-grad-h/-bd-h already are
+     (and the dark palette restates them, so this recolours for free). */
+  .win7 table.is-active > tbody > tr.highlighted {
+    background: var(--w7-el-grad-h);
+    border-color: var(--w7-el-bd-h);
+  }
+
+  /* The keyboard cursor: one dotted focus rectangle around the ROW, the way
+     Win7 drew a focused-but-unselected item. Applying this per cell (tr > *)
+     draws a dotted box around every cell instead — visibly wrong. */
+  .win7 table > tbody > tr.is-cursor {
     outline: 1px dotted var(--w7-el-c);
     outline-offset: -1px;
   }