fix(builder): escape/allowlist all attribute-value sinks incl. numeric/enum props (XSS)

An adversarial pass found 5 Critical XSS sinks where props declared number/enum
in TypeScript were interpolated raw into exported HTML attribute values,
trusting the type — but nothing enforces it at runtime (AI update_props only
validates node_id; deserialized saved state is untyped JSON). Fixed all 5
(NumberCounter data-target, StarRating aria-label, FormContainer method,
ContactForm/InputField input type) plus 6 sibling sinks found by an exhaustive
audit of every attribute-value interpolation across src/components: a
JS-source injection into ContentSlider's inline setInterval script, a
prototype-pollution-adjacent allowlist gap in Section's divider-shape lookup,
TextareaField rows, Testimonials rating aria-label, HeroSimple textAlign, and
MapEmbed zoom. Adds shared sanitizeFormMethod/sanitizeInputType allowlist
helpers to utils/escape.ts alongside the existing escapeAttr/safeUrl/cssValue
primitives. Every fix is TDD'd: a malicious-value test reproduces the raw
injection against the pre-fix code, then passes after the fix.

502 tests green (npx vitest run), tsc + vite build green (npm run build).

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

craft/src/components/layout/Section.tsx

@@ -38,7 +38,14 @@ const ShapeDivider: React.FC<{
   position: 'top' | 'bottom';
 }> = ({ shape, color, height, position }) => {
   if (!shape || shape === 'none') return null;
-  const path = DIVIDER_PATHS[shape];
+  // `shape` is attacker-controlled (AI update_props / deserialized state) and
+  // not runtime-type-checked. A plain-object index lookup with a string key
+  // like '__proto__', 'toString', or 'constructor' returns an INHERITED
+  // Object.prototype value (not undefined), which would otherwise leak
+  // "[object Object]" / a function's source text into the SVG `d` attribute
+  // below. hasOwnProperty restricts the lookup to the real allowlisted keys.
+  if (!Object.prototype.hasOwnProperty.call(DIVIDER_PATHS, shape)) return null;
+  const path = DIVIDER_PATHS[shape as Exclude<DividerShape, 'none'>];
   if (!path) return null;
 
   const isTop = position === 'top';
@@ -162,7 +169,10 @@ function buildDividerHtml(
   position: 'top' | 'bottom',
 ): string {
   if (!shape || shape === 'none') return '';
-  const path = DIVIDER_PATHS[shape];
+  // See the matching hasOwnProperty guard in <ShapeDivider> above -- same
+  // prototype-pollution-shaped lookup, same fix.
+  if (!Object.prototype.hasOwnProperty.call(DIVIDER_PATHS, shape)) return '';
+  const path = DIVIDER_PATHS[shape as Exclude<DividerShape, 'none'>];
   if (!path) return '';
 
   const isTop = position === 'top';