feat(v5.9.0): AI Writing Assist - slash /ai, autocompletion, AI properties

- Service app/services/ai_writing.py: 6 actions sans outils (write, summarize,
  translate, continue, autocomplete, properties) + replis deterministes offline
- Endpoints POST /api/agent/writing et /api/agent/writing/properties
- Editeur: groupe slash AI (Write/Summarize/Translate/Continue) via E.aiSlash
- Autocompletion inline AIAC (suggestion ~900ms, Tab accepte, Escape rejette)
- Database: bouton AI fill (suggestions de proprietes Status/Priority/Resume)
- Tests tests/test_ai_writing.py (+29) ; version 5.9.0 (VERSION, main.py)
- CHANGELOG + ROADMAP v5.9.0 completes

app/templates/_database_table_scripts.html

@@ -84,7 +84,7 @@
                 h += '</div><div class="db-col-resize-handle" data-prop-id="'+prop.id+'"></div></th>';
             }
             h += '<th class="db-th db-th-add-prop"><button class="db-add-prop-btn db-show-prop-modal-btn">+ Add property</button></th>';
-            h += '<th class="db-th" style="width:40px;min-width:40px"></th>';
+            h += '<th class="db-th" style="width:72px;min-width:72px"></th>';
             h += '</tr></thead>';
 
             // Body
@@ -104,7 +104,7 @@
                     }
                     h += '</div></td>';
                 }
-                h += '<td class="db-td db-td-open db-hover-only" style="visibility:hidden"><button class="db-open-btn db-open-page-btn" data-page-id="'+cp.id+'" title="Open">↗</button></td>';
+                h += '<td class="db-td db-td-open db-hover-only" style="visibility:hidden;white-space:nowrap"><button class="db-ai-btn db-ai-fill-btn" data-page-id="'+cp.id+'" title="Remplir les propriétés avec l\'IA" style="background:none;border:none;cursor:pointer;font-size:14px;padding:2px 4px;color:var(--text-dim)">✨</button><button class="db-open-btn db-open-page-btn" data-page-id="'+cp.id+'" title="Open">↗</button></td>';
                 h += '</tr>';
             }
             // Empty rows + New Page at bottom
@@ -141,6 +141,13 @@
                     openPageInSidePeek(parseInt(this.dataset.pageId));
                 };
             });
+            // AI fill properties
+            containerEl.querySelectorAll('.db-ai-fill-btn').forEach(btn => {
+                btn.onclick = function(e) {
+                    e.stopPropagation();
+                    aiFillRow(parseInt(this.dataset.pageId));
+                };
+            });
             // Hover
             containerEl.querySelectorAll('.db-row').forEach(row => {
                 row.onmouseenter = function() { this.querySelectorAll('.db-hover-only').forEach(el => el.style.visibility = 'visible'); };
@@ -249,6 +256,53 @@
             cellEl.onclick = function(e) { if(!state.editingCell && !e.target.closest('.db-open-btn')) startEditCell(pageId,propId,cellEl); };
         }
 
+        // ── v5.9.0: AI property suggestions ──
+        async function aiFillRow(pageId) {
+            const cp = state.pages.find(p => p.id === pageId);
+            if (!cp) return;
+            const props = state.properties.filter(p => p.prop_type !== 'title');
+            if (!props.length) {
+                if (typeof window.showToast === 'function') window.showToast('Aucune propriété à remplir');
+                return;
+            }
+            const payload = {
+                title: cp.title || '',
+                content: cp.content || '',
+                properties: props.map(p => ({ name: p.name, type: p.prop_type }))
+            };
+            if (typeof window.showToast === 'function') window.showToast('✨ FlowDeck AI : analyse en cours…');
+            try {
+                const r = await fetch('/api/agent/writing/properties', {
+                    method: 'POST',
+                    headers: { 'Content-Type': 'application/json', 'X-CSRF-Token': getCsrf() },
+                    body: JSON.stringify(payload)
+                });
+                const d = await r.json();
+                if (!d || !d.ok) {
+                    if (typeof window.showToast === 'function') window.showToast((d && d.error) || 'Échec de la génération');
+                    return;
+                }
+                let pv;
+                try { pv = typeof cp.property_values_json === 'string' ? JSON.parse(cp.property_values_json) : (cp.property_values_json || {}); }
+                catch (e) { pv = {}; }
+                let filled = 0;
+                for (const p of props) {
+                    const v = d.suggestions ? d.suggestions[p.name] : undefined;
+                    if (v !== undefined && v !== null && v !== '') { pv[String(p.id)] = v; filled++; }
+                }
+                cp.property_values_json = pv;
+                await fetch('/db/pages/' + pageId + '/api', {
+                    method: 'PUT',
+                    headers: { 'Content-Type': 'application/json', 'X-CSRF-Token': getCsrf() },
+                    body: JSON.stringify({ title: cp.title, properties: pv })
+                });
+                render();
+                if (typeof window.showToast === 'function') window.showToast(filled ? ('✨ ' + filled + ' propriété(s) remplie(s)') : 'Aucune suggestion disponible');
+            } catch (e) {
+                if (typeof window.showToast === 'function') window.showToast('Erreur IA');
+            }
+        }
+
         async function addNewPage() {
             try {
                 const r = await fetch('/api/collections/'+collectionId+'/pages',{method:'POST',headers:{'Content-Type':'application/json','X-CSRF-Token':getCsrf()},body:JSON.stringify({title:''})});