Add PrintVault module: 3D print file manager integrated in HouseHub

- printvault.php: SPA with model grid, sidebar (categories + type filters), search
- modules/printvault/api.php: PHP proxy to PrintVault API (auth + CORS)
- modules/printvault/assets/printvault.js: model grid, upload modal, detail modal
- modules/printvault/assets/printvault.css: full light/dark theme
- Upload: drag&drop + form (name, category, tags)
- Detail modal: metadata, dimensions, GCode info, download, delete, "Voir en 3D" → PrintVault
- Integrated in header nav, home page, settings; translations fr/en/ca

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

index.php

@@ -127,6 +127,15 @@ if ($_has_custom_bg): ?>
       </a>
       <?php endif; ?>
 
+      <?php if (in_array('printvault', $mods)): ?>
+      <a href="/printvault.php" class="pf-module-card">
+        <div class="pf-card-icon">🖨️</div>
+        <h3 class="pf-card-title"><?= tr('mod_printvault_name') ?></h3>
+        <div class="pf-card-desc"><?= tr('mod_printvault_desc') ?></div>
+        <span class="pf-card-cta"><?= tr('cta_print') ?></span>
+      </a>
+      <?php endif; ?>
+
     </div>
   </section>
 </div>