feat(render): card owner pill + short ISO date span

closes board-viewer-card-meta-fix

Review found two acceptance fields missing from cards:
- project_owner was in JSON but never displayed
- last_commit_iso was only consumed for relative age; no absolute date

Now both rendered (server-side src/render.ts + client-side static/board.js
in sync), with 4 new TDD tests:
- renders owner pill when project_owner is set
- omits owner pill when empty
- renders short YYYY-MM-DD date when last_commit_iso is set
- omits date span when null

CSS: .badge.owner = transparent + border (visually distinct from solid
.badge.project), .date = small muted tabular-nums. Smoke-verified in browser.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

static/board.css

@@ -245,3 +245,15 @@ aside.drawer[hidden] {
 .badge.status {
   background: var(--badge-bg);
 }
+
+.badge.owner {
+  background: transparent;
+  border: 1px solid var(--border);
+  color: var(--muted);
+}
+
+.date {
+  font-variant-numeric: tabular-nums;
+  color: var(--muted);
+  font-size: 0.7rem;
+}

static/board.js

@@ -76,13 +76,21 @@ function truncate(s, max) {
 function renderCard(rec, now, mode) {
   const age = formatAge(rec.last_commit_iso, now);
   const archived = isArchived(rec, now);
-  const meta = mode === 'by-project'
+  const primary = mode === 'by-project'
     ? `<span class="badge status">${STATUS_EMOJI[rec.status]} ${STATUS_LABEL[rec.status]}</span>`
     : `<span class="badge project">${escapeHtml(rec.project)}</span>`;
+  const ownerPill = rec.project_owner
+    ? `<span class="badge owner">${escapeHtml(rec.project_owner)}</span>`
+    : '';
+  const dateSpan = rec.last_commit_iso
+    ? `<span class="date" title="${escapeHtml(rec.last_commit_iso)}">${escapeHtml(rec.last_commit_iso.slice(0, 10))}</span>`
+    : '';
   return `<li class="card" data-slug="${escapeHtml(rec.slug)}" data-raw-url="${escapeHtml(rec.raw_url)}" data-archived="${archived ? 'true' : 'false'}">
     <div class="card-title">${escapeHtml(truncate(rec.title, 80))}</div>
     <div class="card-meta">
-      ${meta}
+      ${primary}
+      ${ownerPill}
+      ${dateSpan}
       ${age === null ? '' : `<span class="age">${escapeHtml(age)}</span>`}
     </div>
   </li>`;