Fix build-breaking ident rewrite, blank-iframe grafting, and layout-gate regressions

Round-3 fixes from gate validation + human visual review of fresh
cropin.com and ooni.com clones:

- app.ts: section data-var rename used an unanchored substring replace,
  so Tile2_data matched inside MediaTile2_data and emitted a corrupted
  Mediatile2Data usage (ReferenceError at prerender). Word-boundary
  regex; every map site now shares one derivation.
- graft.ts: about:blank iframes were blanket-skipped, missing the
  Klaviyo newsletter form (mounted into a blank same-origin frame via
  JS) — the audit's #1 complaint. Blank frames now graft; the
  visibility gate still excludes 0-size tracking pixels.
- walker.ts: isVisible() now rejects boxes wholly outside the viewport
  (off-left always; off-right only when the page isn't horizontally
  scrollable; fixed boxes fully above/below), so a closed slide-in
  drawer's contents no longer count as expected text (91.8% -> 93.4%).
- css.ts: four sizing-regime corrections — pin captured px for
  circular shrink-0 slides (Splide slide chain collapsed 0x0);
  flex-basis:100% for full-width shrink-0 slides; keep fixed-px grid
  templates for scrolling track lists (repeat(N,1fr) squished a
  50-track carousel); single full-bleed fixed track -> minmax(0,1fr);
  keep authored heights whose in-flow children are fill children
  (aspect-video heroes inflated 240 -> 720px); width:100% for
  inset-spanned aspect boxes.

Gate scores: ooni home 88.7 -> 93.3 (responsive 32 fails -> pass),
pizza-ovens 90.8 -> 97.6 (perceptual 46.7% -> 17.2%).
107/107 compiler tests, all workspaces green.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

compiler/src/generate/app.ts

@@ -2053,7 +2053,10 @@ export function sectionFiles(sreg: SectionRegistry | undefined, reg: ComponentRe
     let body = jsx;
     for (const v of usedData) {
       const p = dataProps.get(v) ?? camelVar(v);
-      if (p !== v) body = body.split(`${v}.map(`).join(`${p}.map(`);
+      // Word-boundary rewrite: a plain substring replace of `${v}.map(` would also match
+      // inside a longer var (e.g. `Tile2_data` is a suffix of `MediaTile2_data`), corrupting
+      // it. Anchor on a non-identifier char before the name so only the whole var is renamed.
+      if (p !== v) body = body.replace(new RegExp(`(^|[^\\w$])${escapeRegExp(v)}\\.map\\(`, "g"), `$1${p}.map(`);
       const binding = contentBindings.get(v);
       if (binding) {
         const alias = safeIdent(`${p}Content`, "contentData");