fix(web): align draft pane styles with design mockup

- Add panel padding and vertical divider between Agent/File Editor panels
- Add horizontal divider rule for stacked narrow layout
- Remove CTA text from provider buttons (not in design)
- Lower responsive breakpoint from 36rem to 28rem so side-by-side layout persists longer
- Add border-left rule to base CSS block for consistency

Author: pallyoung

packages/web/src/features/agent-panes/views/shared/draft-launcher.tsx

@@ -308,9 +308,6 @@ export const DraftLauncher: FC<DraftLauncherProps> = ({
                           <span className="agent-provider-card-title-row">
                             <span className="agent-provider-card-title">{provider.title}</span>
                           </span>
-                          <span className="agent-provider-card-cta">
-                            {getProviderCta(provider.id)}
-                          </span>
                           {isBusy ? (
                             <span className="agent-provider-card-status">
                               {t("provider.install.status.installing")}

packages/web/src/styles/components.css

@@ -4090,6 +4090,10 @@ body.is-dragging-pane {
   flex-direction: row;
 }
 
+.agent-draft-panel + .agent-draft-panel {
+  border-left: 1px solid var(--border-default);
+}
+
 /* ========== Session Card ========== */
 .session-card {
   display: flex;
@@ -7298,6 +7302,11 @@ textarea.input {
   flex-direction: column;
   align-items: flex-start;
   gap: var(--sp-3);
+  padding: var(--sp-5);
+}
+
+.agent-draft-panel + .agent-draft-panel {
+  border-left: 1px solid var(--border-default);
 }
 
 .agent-draft-panel-header {
@@ -7486,12 +7495,19 @@ textarea.input {
   color: var(--text-tertiary);
   padding-top: var(--sp-3);
   border-top: 1px solid var(--border-default);
+  margin-top: var(--sp-2);
 }
 
-@container (max-width: 36rem) {
+@container (max-width: 28rem) {
   .agent-draft-component-row {
     flex-direction: column;
   }
+
+  .agent-draft-panel + .agent-draft-panel {
+    border-left: none;
+    border-top: 1px solid var(--border-default);
+    padding-left: var(--sp-5);
+  }
 }
 
 .session-card {