chore(home): remove "Export report" button

The disabled "Export report" placeholder is gone — it wasn't tied to
a real feature and was just noise in the action bar. Action bar is
back to two buttons (Run analysis · Clear results) on a 1:1:4
column split. ``upload.export_report`` keys removed from en + es
i18n packs.

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

src/i18n/packs/en.json

@@ -32,7 +32,6 @@
     "intro_multi": "Drop files below. Each one is analyzed locally — nothing leaves this computer.",
     "uploader_label_multi": "Import CSV, TSV, or Excel files",
     "clear_results": "Clear results",
-    "export_report": "Export report",
     "empty_state": "Import one or more files to begin. Your data never leaves this computer."
   },
   "findings": {