Restructure Settings nav, modernize import page, dedup/genres UX polish

Settings is now one top-nav entry with Credentials and Jobs as sidebar
sub-pages (jobs moved from /jobs to /settings/jobs). Manual import page
replaces the bare file input and free-text filename field with a drag-drop
dropzone and a proper file-picker table. Genres page drops the "force"
checkbox for two explicit buttons (Preview / Fix genres now). Dedup's
"Scan now" runs both the file-naming and acoustic passes together, and the
table labels which pass caught each candidate instead of showing the raw
pass name. .btn-ghost gets a visible border so it reads as a real button
next to Delete/Danger actions instead of looking unaligned. Job names
throughout the UI are now human-readable instead of raw job_key strings.

Also includes the fpcalc exit-code fix from earlier (fingerprint index
was discarding valid fingerprints on files with a benign decode warning).

app/templates/dashboard.html

@@ -76,7 +76,7 @@
       {% set status_badge = {"running": "badge-info badge-pulse", "success": "badge-success", "failed": "badge-danger", "skipped_lock": "badge-muted"} %}
       {% for run in recent_runs %}
       <tr>
-        <td>{{ run.job_key }}</td>
+        <td>{{ humanize_job_key(run.job_key) }}</td>
         <td><span class="badge {{ status_badge.get(run.status, 'badge-muted') }}">{{ run.status }}</span></td>
         <td class="muted">{{ run.triggered_by }}</td>
         <td>{{ run.summary or "—" }}</td>
@@ -87,5 +87,5 @@
     </tbody>
   </table>
 </div>
-<p><a href="/jobs">See all jobs &rarr;</a></p>
+<p><a href="/settings/jobs">See all jobs &rarr;</a></p>
 {% endblock %}