Sessions: edit form, soft-delete, lazy creation, chat as separate page

- Session click opens edit form (name, description, image, agent) instead of chat
- Chat is now a separate route (#chat/{id}), opened via button
- Sessions created on save, not on click
- Soft-delete for sessions (is_deleted flag)
- Delete button in session form
- Removed title double-click editing from chat
- Card images now square (aspect-ratio: 1)
- New Session as placeholder card

wwwroot/css/main.css

@@ -69,19 +69,63 @@ body {
 .card {
   background: var(--f3-bg);
   border: var(--border-width) solid var(--f3-border);
-  padding: var(--s4);
   display: flex;
   flex-direction: column;
-  gap: var(--s2);
+  overflow: hidden;
 }
 
 .card.clickable { cursor: pointer; }
 .card.clickable:hover { border-color: var(--primary); }
 
-.card-icon { font-size: 2em; }
+.card-image {
+  aspect-ratio: 1;
+  background: var(--f2-bg);
+  overflow: hidden;
+}
+
+.card-image img {
+  width: 100%;
+  height: 100%;
+  object-fit: cover;
+}
+
+.card-body {
+  padding: var(--s3);
+  display: flex;
+  flex-direction: column;
+  gap: var(--s1);
+}
+
+.card-title-row {
+  display: flex;
+  align-items: center;
+  gap: var(--s2);
+}
+
+.card-title {
+  font-weight: bold;
+  white-space: nowrap;
+  overflow: hidden;
+  text-overflow: ellipsis;
+}
+
+.card-desc {
+  display: -webkit-box;
+  overflow: hidden;
+}
+
+.badge {
+  padding: var(--s1) var(--s2);
+  background: var(--f1-bg);
+  border: var(--border-width) solid var(--f2-border);
+  white-space: nowrap;
+  flex-shrink: 0;
+}
 
 .card.placeholder {
   border-style: dashed;
+  align-items: center;
+  justify-content: center;
 }
 
 /* ── Session Page ── */
@@ -189,23 +233,3 @@ body {
   background: #ff6b6b;
   color: var(--f1-bg);
 }
-
-/* ── Agent Card Avatar ── */
-
-.agent-card-avatar {
-  width: 40px;
-  height: 40px;
-  background: var(--f2-bg);
-  border: var(--border-width) solid var(--f2-border);
-  display: flex;
-  align-items: center;
-  justify-content: center;
-  font-size: 1.2em;
-  overflow: hidden;
-}
-
-.agent-card-avatar img {
-  width: 100%;
-  height: 100%;
-  object-fit: cover;
-}