fix(e2e,landing): robust path escaping (CodeQL) + unique file-tools card

- tests/e2e/helpers.ts: build the sharp script path via JSON.stringify
  instead of single-quote-only replace (CodeQL js/incomplete-sanitization,
  high: backslashes were not escaped). Proper fix, no suppression.
- landing CategoryCards: rename the file-modality marketing card to
  "File Tools" (matches the Image/Video/Audio Tools siblings and is
  unique vs the 23 "Files" tool pills, which broke the e2e locator).
  Modality label stays "Files" everywhere it is the actual modality.

apps/landing/src/components/CategoryCards.astro

@@ -51,7 +51,7 @@ const MODALITIES = [
   {
     id: "file",
     section: "files",
-    label: "Files",
+    label: "File Tools",
     blurb: "Convert and transform",
     icon: "Database",
     color: "#5C8642",