Consolidate OpenCode Chain into OpenCode Models section

- Removed separate OpenCode Chain card
- Integrated chain functionality as subsection within OpenCode Models
- Chain form and list now appear below the models list
- Added styling to distinguish the chain subsection

chat/public/admin.html

@@ -16,6 +16,18 @@
     }
     /* Slightly tighten cards on the build page */
     body[data-page="build"] .admin-card { padding: 12px; }
+    
+    /* Chain section styling */
+    .chain-section {
+      margin-top: 24px;
+      padding-top: 16px;
+      border-top: 2px solid var(--border);
+    }
+    .chain-section h4 {
+      margin: 0 0 8px 0;
+      font-size: 14px;
+      color: var(--muted);
+    }
   </style>
 
     <!-- PostHog Analytics -->
@@ -67,15 +79,15 @@
       </div>
     </div>
 
-    <!-- Section 1: OpenCode Models -->
+    <!-- Section 1: OpenCode Models (with integrated Chain) -->
     <div class="admin-card">
       <header>
         <h3>OpenCode Models</h3>
         <div class="pill">Backend</div>
       </header>
-      <p style="margin-top:0; color: var(--muted);">Add models from OpenCode. These models process requests and use the OpenCode Chain below for fallback when rate limits are reached.</p>
+      <p style="margin-top:0; color: var(--muted);">Add models from OpenCode. These models process requests and can fall back to the provider chain when rate limits are reached.</p>
       
-      <!-- Add Form -->
+      <!-- Add Model Form -->
       <form id="opencode-model-form" class="admin-form" style="margin-bottom: 24px;">
         <label>
           Choose from OpenCode
@@ -112,25 +124,21 @@
         <div class="status-line" id="opencode-model-status"></div>
       </form>
 
-      <!-- List -->
+      <!-- Models List -->
       <header style="margin-top: 24px; border-top: 1px solid var(--border); padding-top: 16px;">
         <h3>OpenCode Models List</h3>
         <div class="pill" id="opencode-models-count">0</div>
       </header>
       <p class="muted" style="margin-top:0;">Arrange the order below. This controls which model is primary for OpenCode requests.</p>
       <div id="opencode-models-list" class="admin-list"></div>
-    </div>
 
-    <!-- Section 2: OpenCode Chain (Fallback) -->
+      <!-- Chain Section (integrated) -->
-    <div class="admin-card" style="margin-top: 16px;">
+      <div class="chain-section">
-      <header>
+        <h4>Fallback Chain (for when rate limits are reached)</h4>
-        <h3>OpenCode Chain</h3>
+        <p class="muted" style="margin-top:0; margin-bottom: 12px;">When the primary OpenCode model hits rate limits, the system falls back through these providers in order.</p>
-        <div class="pill">Fallback</div>
-      </header>
-      <p style="margin-top:0; color: var(--muted);">When rate limits are reached or errors occur, the system falls back through this chain of providers.</p>
         
-      <!-- Add Form -->
+        <!-- Add to Chain Form -->
-      <form id="chain-form" class="admin-form" style="margin-bottom: 24px;">
+        <form id="chain-form" class="admin-form" style="margin-bottom: 16px;">
           <div class="admin-grid" style="grid-template-columns: 1fr 2fr; gap: 12px;">
             <label>
               Provider
@@ -151,22 +159,24 @@
               <input id="chain-model" type="text" placeholder="e.g., anthropic/claude-3.5-sonnet" required />
             </label>
           </div>
-        <div class="admin-actions">
+          <div class="admin-actions" style="margin-top: 12px;">
-          <button type="submit" class="primary">Add to Chain</button>
+            <button type="submit" class="primary">Add to Fallback Chain</button>
           </div>
           <div class="status-line" id="chain-status"></div>
         </form>
 
-      <!-- List -->
+        <!-- Chain List -->
-      <header style="margin-top: 24px; border-top: 1px solid var(--border); padding-top: 16px;">
+        <div style="margin-top: 16px;">
-        <h3>Chain Order</h3>
+          <div style="display: flex; justify-content: space-between; align-items: center; margin-bottom: 8px;">
-        <div class="pill" id="chain-count">0</div>
+            <span class="muted">Fallback Chain Order</span>
-      </header>
+            <span class="pill" id="chain-count">0</span>
-      <p class="muted" style="margin-top:0;">The system tries providers in this order. Use arrows to reorder.</p>
+          </div>
           <div id="chain-list" class="admin-list"></div>
         </div>
+      </div>
+    </div>
 
-    <!-- Section 3: Public Models (Completely Separate) -->
+    <!-- Section 2: Public Models (Completely Separate) -->
     <div class="admin-card" style="margin-top: 16px;">
       <header>
         <h3>Public Models</h3>