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/partials/newConference.htm

@@ -108,7 +108,8 @@
         </div>
         <div class="form-check">
           <input class="form-check-input" type="checkbox" id="notebook" name="notebook" v-field="{ state: viewState, set: value =&gt; { options.options.notebook = value }, value: options?.options?.notebook, form: &quot;conference&quot;, options: {} }">
-          <label class="form-check-label" for="notebook">Display Notebooks</label>
+          <label class="form-check-label" for="notebook">Display notebooks</label>
+          <small class="form-text text-muted">Render Jupyter notebooks instead of raw JSON.</small>
         </div>
       </section>