site-builder: dynamic CTAs, section anchors, edit-with-Sitesmith

Three related features:

1. Dynamic CTA buttons on HeroSimple, CTASection, CallToAction.
   New shared ctas[] array (text + href + variant + target) replaces the
   primary/secondary pair. Settings panel gets add/remove/reorder controls.
   Legacy fields stay readable for backwards compat — first user edit
   migrates the section onto the new array.

2. Anchor IDs on all layout/section components (Container, Section,
   BackgroundSection, ColumnLayout, plus 6 section blocks done by parallel
   subagent, plus Hero/CTA/CallToAction). Anchor input lives in the
   settings panel with an "auto from heading" button that walks the
   subtree for the first Heading.text. Renders as id="..." on the
   outermost element so #anchor URLs resolve.

3. Edit-with-Sitesmith targeted invocation. Right-click → "Ask Sitesmith"
   and a button at the top of the right-side settings panel both open the
   modal pre-targeted at the selected node. The node's serialized subtree
   is sent to the server; system prompt is augmented to require a patch
   with replace_node. Editor lifts modal state into a new SitesmithContext.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

craft/src/hooks/useSitesmith.ts

@@ -34,14 +34,20 @@ export function useSitesmith(siteId: number) {
 
   useEffect(() => { void refreshEntitlement(); void fetchHistory(); }, [refreshEntitlement, fetchHistory]);
 
-  const send = useCallback(async (userText: string, canvasSummary: string): Promise<SendResult> => {
+  const send = useCallback(async (
+    userText: string,
+    canvasSummary: string,
+    target?: { node_id: string; display_name: string; tree_json: string },
+  ): Promise<SendResult> => {
     if (!whpConfig) return { ok: false, status: 'BLOCKED', message: 'No WHP config' };
     setMessages((m) => [...m, { role: 'user', content: userText, response_type: null, created_at: new Date().toISOString() }]);
+    const body: Record<string, unknown> = { site_id: siteId, message: userText, canvas_summary: canvasSummary };
+    if (target) body.target = target;
     const r = await fetch(`${apiBase(whpConfig.apiUrl)}?action=send`, {
       method: 'POST',
       credentials: 'include',
       headers: { 'Content-Type': 'application/json', 'X-CSRF-Token': whpConfig.csrfToken },
-      body: JSON.stringify({ site_id: siteId, message: userText, canvas_summary: canvasSummary }),
+      body: JSON.stringify(body),
     });
     const j: SendResult = await r.json();
     void fetchHistory();