fix: polish explorer, error states and page alignment

- Explorer: 13px code, page-coloured dark editor, padded Markdown with a
  readable width, full repository ID on hover, sidebar footer kept clear
  of the floating Ko-fi button.
- Explorer errors render as a card with links home and to the FAQ; the
  empty action bar and Raw/Download buttons are hidden.
- Unknown error codes show the generic message instead of the raw
  ERRORS.<code> key.
- All app pages share one content column; New anonymization starts at
  the top instead of floating mid-screen.
- Status page: spaced action buttons, aligned status pill, no second
  Ko-fi embed under the support cards.
- Claim placeholders; consistent notebook option on new conferences.

Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>

public/script/main.js

@@ -18,7 +18,9 @@ import { fieldDirective, formDirective, submitForm } from "./forms.js";
 const sessionKey = Symbol("session");
 export const serverPaths = /^\/(w|api|github)(\/|$)/;
 function translate(key, params = {}) {
-  const message = key?.split(".").reduce((value, part) => value?.[part], translations);
+  let message = key?.split(".").reduce((value, part) => value?.[part], translations);
+  // Unknown error codes would otherwise surface as the raw "ERRORS.code" key.
+  if (message == null && key?.startsWith("ERRORS.")) message = translations.ERRORS.unknown_error;
   return String(message ?? key ?? "").replace(/{{\s*([^}]+?)\s*}}/g, (_, name) => params[name] ?? "");
 }
 const fmt = { ...formatters, translate };