feat(modality): rename "file" modality label "Data" -> "Files"

The fifth user-facing group is now Image, Video, Audio, PDF, Files
(internal modality id stays "file"; section.ts "files" was already
"Files"). Updates modality.ts label + comment, all 21 i18n locales
(categories.data "Data Files"->"Files", modalities.documentsAndFiles
"PDF & Data"->"PDF & Files", dead homePage.data), landing cards/hero
search/tools filter, docs headings, and e2e modality-tab assertions
(/^Data/ -> /^Files/, which had been failing).

apps/web/src/lib/tool-display-modes.ts

@@ -192,7 +192,7 @@ export const TOOL_DISPLAY_MODES: Record<string, DisplayMode> = {
   "epub-convert": "no-comparison",
   "to-epub": "no-comparison",
 
-  // Data tools
+  // File tools
   "chart-maker": "no-comparison",
   "csv-excel": "no-comparison",
   "csv-json": "no-comparison",

apps/web/src/lib/tool-registry.tsx

@@ -1106,7 +1106,7 @@ const ENTRY_CONFIG: ReadonlyArray<[string, RegistryEntryConfig]> = [
   ["html-to-pdf", { accept: ".html,.htm", Settings: HtmlToPdfSettings }],
   ["markdown-to-pdf", { accept: ".md,.markdown", Settings: MarkdownToPdfSettings }],
 
-  // Data tools
+  // File tools
   ["chart-maker", { accept: ".csv,.json", Settings: ChartMakerSettings }],
   ["csv-excel", { accept: ".csv,.tsv,.xlsx", Settings: CsvExcelSettings }],
   ["csv-json", { accept: ".csv,.tsv,.json", Settings: CsvJsonSettings }],