Fix uncontrolled input warning on leads admin page

Use defaultValue instead of value for the Loop Path input since it
only saves on blur, not on every keystroke.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

src/app/(dashboard)/leads/admin/page.tsx

@@ -163,7 +163,7 @@ export default function LeadsAdminPage() {
               <label className="text-xs text-muted block mb-1">Loop Path</label>
               <input
                 type="text"
-                value={config.prospecting_loop_path || ''}
+                defaultValue={config.prospecting_loop_path || ''}
                 placeholder="(default: ../BSG Prospecting Loop/sales-agent)"
                 onBlur={e => e.target.value && saveConfig('prospecting_loop_path', e.target.value)}
                 className="w-full text-xs border border-card-border rounded px-2 py-1.5 font-mono"