feat(wiki,templates): v5.11.0 wiki-links & mentions + v5.12.0 templates & page lock (release 5.12.0)

v5.11.0 Wiki-links & mentions de page :
- tokens [[fdpage:ID]] / [[fddate:ISO]] dans le texte des blocs,
  service app/services/wiki_links.py (labels, rendu HTML, extraction)
- taper [[ ouvre le picker de pages (recherche floue, clavier) ;
  le menu @ gagne les sections Pages et Date (today/tomorrow/YYYY-MM-DD)
- chips atomiques contenteditable=false relues en tokens par gtTok()
  (autosave/drag/undo preservent les liens) ; renommage propage via
  GET /board/api/wiki/titles ; backlinks reconnaissent les tokens ;
  page publique rend les chips (echopee)

v5.12.0 Templates & verrouillage :
- template picker global sur + New page : 5 built-in
  (app/services/block_templates.py) + templates perso
  (table page_global_templates, migration 13)
- POST /board/api/page-templates (save current page) + /{id}/use
  (instantiate, id 0 = built-in par cle)
- page lock : POST /api/pages/{id}/lock, garde _ensure_page_editable
  -> 423 en ecriture pour les non-privileged, deblocage par
  locked_by ou admin seulement (403 sinon), banniere + read-only UI
- full-width / small text par page (pages.full_width/font_small,
  POST /api/pages/{id}/options, classes CSS)
- migration 13 : is_locked, locked_by, full_width, font_small,
  page_global_templates

Tests : tests/test_v511_v512_wiki_templates.py (15) ; suite complete
538 verte ; ruff OK ; node --check des templates JS OK.

app/templates/_page_editor_content.html

@@ -473,6 +473,19 @@
                 </div>
                 <div class="more-menu-item" @click="movePage">↗ Move to</div>
                 <div class="more-menu-sep"></div>
+                <div class="more-menu-item" @click="moreOpen=false; toggleLock()">
+                    <span x-text="isLocked ? '🔓 Unlock page' : '🔒 Lock page'"></span>
+                </div>
+                <div class="more-menu-item" @click="moreOpen=false; setPageOption('full_width', !fullWidth)">
+                    ↔ Full width <span x-show="fullWidth" style="margin-left:auto;font-size:11px">✓</span>
+                </div>
+                <div class="more-menu-item" @click="moreOpen=false; setPageOption('font_small', !fontSmall)">
+                    Aa Small text <span x-show="fontSmall" style="margin-left:auto;font-size:11px">✓</span>
+                </div>
+                <div class="more-menu-item" @click="moreOpen=false; saveAsTemplate()">
+                    📑 Save as template
+                </div>
+                <div class="more-menu-sep"></div>
                 <div class="more-menu-item danger" @click="deletePage">
                     {{ fd_icon("trash",14) }} Move to Trash
                 </div>