fix(dashboard): cut duplicate API/icon spam, lazy-load provider assets

Share one /api/models fetch via useModelCaps cache, mount ModelSelectModal
only when open, stop double fetchModelAliases on CLI tool cards, and resolve
provider icons through a session 404 cache with missing PNGs + loading=lazy.
Also include Claude Exa MCP toggle (claude-settings + ClaudeToolCard) that
was already in the working tree.

Co-authored-by: Cursor <cursoragent@cursor.com>

src/shared/components/McpMarketplaceModal.js

@@ -154,7 +154,7 @@ export default function McpMarketplaceModal({ isOpen, onClose, onAdd, addedNames
                   <div className="flex items-start gap-2 px-2 py-2 hover:bg-black/5 dark:hover:bg-white/5">
                     {s.iconUrl ? (
                       // eslint-disable-next-line @next/next/no-img-element
-                      <img src={s.iconUrl} alt="" className="size-7 rounded shrink-0 object-contain" onError={(e) => { e.target.style.display = "none"; }} />
+                      <img src={s.iconUrl} alt="" className="size-7 rounded shrink-0 object-contain" onError={(e) => { e.target.style.display = "none"; }} loading="lazy" decoding="async" />
                     ) : (
                       <div className="size-7 rounded bg-surface shrink-0" />
                     )}