feat(web): click Executions' Started time to toggle relative/absolute

Both renderings are pre-rendered server-side into a <button>'s
data-relative/data-absolute attributes; app.js swaps textContent (and the
hover title, to the opposite value) on click, delegated on document.body
so it survives the card's own 5s htmx poll without needing to re-wire
after every swap. Click again to swap back.

src/ci_orchestrator/web/static/app.css

@@ -501,6 +501,22 @@ input[type="text"], input[type="number"], select {
 /* Muted inline text (e.g. a relative-time suffix next to a file name). */
 .text-dim { color: var(--text-dim); }
 
+/* Executions "Started" cell: reset to read as plain inline text (no button
+ * chrome), with a dotted underline as the click-to-toggle affordance --
+ * not colour alone, same rule the rest of the app follows. app.js swaps
+ * between its data-relative/data-absolute values on click. */
+.time-toggle {
+  background: none;
+  border: none;
+  padding: 0;
+  margin: 0;
+  font: inherit;
+  cursor: pointer;
+  text-decoration: underline dotted;
+  text-underline-offset: 2px;
+}
+.time-toggle:hover { color: var(--text); }
+
 /* ── notices / confirm / result panels ───────────────────────────────── */
 
 .notice {

src/ci_orchestrator/web/static/app.js

@@ -204,6 +204,22 @@
     }
   });
 
+  // Executions "Started" cell: click swaps between the relative and
+  // absolute time already rendered into the button's own data attributes --
+  // no request. Delegated on body (not the button itself) so it keeps
+  // working after the Executions card's own 5s htmx poll replaces the row.
+  document.body.addEventListener("click", function (evt) {
+    var btn = evt.target.closest(".time-toggle");
+    if (!btn) {
+      return;
+    }
+    var next = btn.dataset.showing === "relative" ? "absolute" : "relative";
+    var shown = next === "relative" ? "absolute" : "relative";
+    btn.textContent = btn.dataset[next];
+    btn.title = btn.dataset[shown];
+    btn.dataset.showing = next;
+  });
+
   document.addEventListener("DOMContentLoaded", function () {
     observeStack();
     processSlot(document.getElementById("action-slot"));

src/ci_orchestrator/web/templates/partials/executions.html

@@ -89,7 +89,9 @@
           <td>{{ run.duration_sec | duration }}</td>
           <td>
             {% if run.started %}
-            <span class="text-dim" title="{{ run.started | localtime }}">{{ run.started | relative_time }}</span>
+            <button type="button" class="time-toggle text-dim" data-showing="relative"
+                    data-relative="{{ run.started | relative_time }}" data-absolute="{{ run.started | localtime }}"
+                    title="{{ run.started | localtime }}">{{ run.started | relative_time }}</button>
             {% else %}
             <span class="text-dim">—</span>
             {% endif %}
@@ -137,7 +139,9 @@
           <td><span class="text-dim">—</span></td>
           <td>
             {% if parsed.started %}
-            <span class="text-dim" title="{{ parsed.started | localtime }}">{{ parsed.started | relative_time }}</span>
+            <button type="button" class="time-toggle text-dim" data-showing="relative"
+                    data-relative="{{ parsed.started | relative_time }}" data-absolute="{{ parsed.started | localtime }}"
+                    title="{{ parsed.started | localtime }}">{{ parsed.started | relative_time }}</button>
             {% else %}
             <span class="text-dim">—</span>
             {% endif %}