feat(ui): natural markdown rendering in editor blocks & agent panel

- Editor: applyAIBlocks() and fdApplyDocument(replace) now convert agent
  markdown into real blocks via md2b() (## -> heading_2, GFM tables ->
  table block, ` -> code, lists, to-do, quote, divider). No more literal
  '## ' shown.
- Editor: inline markdown rendered in blocks via mdEsc() (bold/italic/
  inline-code/links/strikethrough) in renderBlock for paragraphs, headings,
  lists, to-do, toggle, quote, callout, code.
- Agent panel: renderMarkdown() renders assistant responses as HTML (H1-H4,
  GFM tables, code blocks, lists+checkboxes, quotes, hr, inline marks);
  content escaped before rendering (XSS-safe vs LLM). CSS .fd-md-* added.
- VERSION + app.main -> 5.1.1; CHANGELOG updated.
- 271 tests pass (no regression); markdown render verified in Node; editor &
  panel render 200 with new components.

app/templates/_page_editor_scripts.html

@@ -18,6 +18,17 @@
     function ce(e){const r=document.createRange();r.selectNodeContents(e);r.collapse(false);window.getSelection().removeAllRanges();window.getSelection().addRange(r);}
     function cs(e){const r=document.createRange();r.selectNodeContents(e);r.collapse(true);window.getSelection().removeAllRanges();window.getSelection().addRange(r);}
     function esc(s){return s.replace(/&/g,'&amp;').replace(/</g,'&lt;').replace(/>/g,'&gt;');}
+    // Escape then render inline markdown (bold/italic/code/links/strikethrough)
+    // so agent-generated content displays without raw `**`/backtick characters.
+    function mdEsc(s){
+      if(!s) return '';
+      return String(s).replace(/&/g,'&amp;').replace(/</g,'&lt;').replace(/>/g,'&gt;')
+        .replace(/`([^`]+)`/g,'<code>$1</code>')
+        .replace(/\*\*([^*]+)\*\*/g,'<strong>$1</strong>')
+        .replace(/\*([^*]+)\*/g,'<em>$1</em>')
+        .replace(/~~([^~]+)~~/g,'<s>$1</s>')
+        .replace(/\[([^\]]+)\]\((https?:[^)\s]+)\)/g,'<a href="$2" target="_blank" rel="noopener noreferrer">$1</a>');
+    }
 
     const CALLOUT_ICONS=['💡','💡','📌','⚠️','ℹ️','✅','❌','🚀','🔔','📣','⭐','❤️','🔥','💬','👀','🧠','🎯','🔑','📅','💰','💡','📚','🧪','🌍'];
 
@@ -223,11 +234,11 @@
       }
       const ph=b.type==='heading_1'?'Heading 1':b.type==='heading_2'?'Heading 2':b.type==='heading_3'?'Heading 3':b.type==='heading_4'?'Heading 4':b.type==='bulleted_list'?'List':b.type==='numbered_list'?'List':b.type==='to_do'?'To-do':b.type==='toggle'?'Toggle list':b.type==='quote'?'Empty quote':b.type==='code'?'Type code...':b.type==='callout'?'Type something...':'Press \'/\' for commands...';
       let inner='';
-      if(b.type==='to_do')inner=`<input type="checkbox" class="todo-checkbox" ${b.checked?'checked':''} onchange="E._doToggle('${b.id}',this.checked)"><div data-bid="${b.id}" contenteditable="true" data-placeholder="${ph}" spellcheck="false">${esc(b.content)}</div>`;
-      else if(b.type==='toggle')inner=`<div class="toggle-title-row"><button class="toggle-chevron ${b.expanded?'open':''}" onclick="E._doToggleExpand('${b.id}')">▶</button><div class="toggle-title" data-bid="${b.id}" contenteditable="true" data-placeholder="${ph}" spellcheck="false">${esc(b.content)}</div></div><div class="toggle-children" ${(b.expanded===false)?'style="display:none"':''}>${(b.children||[]).map((ch)=>renderNestedBlock(ch)).join('')}</div>`;
-      else if(b.type==='code')inner=`<div class="code-lang-label">${b.language||'Plain Text'}</div><pre><code data-bid="${b.id}" contenteditable="true" spellcheck="false">${esc(b.content)}</code></pre>`;
-      else if(b.type==='callout')inner=`<span class="callout-icon" onclick="E._toggleCalloutIcon('${b.id}')" title="Change icon">${b.icon||'💡'}</span><div data-bid="${b.id}" contenteditable="true" data-placeholder="${ph}" spellcheck="false">${esc(b.content)}</div><div class="callout-icon-picker" id="callout-picker-${b.id}" style="display:none">${CALLOUT_ICONS.map(function(i){return '<button type="button" class="callout-icon-opt" onclick="E._setCalloutIcon(\''+b.id+'\',\''+i+'\')">'+i+'</button>';}).join('')}</div>`;
-      else inner=`<div data-bid="${b.id}" contenteditable="true" data-placeholder="${ph}" spellcheck="false">${esc(b.content)}</div>`;
+      if(b.type==='to_do')inner=`<input type="checkbox" class="todo-checkbox" ${b.checked?'checked':''} onchange="E._doToggle('${b.id}',this.checked)"><div data-bid="${b.id}" contenteditable="true" data-placeholder="${ph}" spellcheck="false">${mdEsc(b.content)}</div>`;
+      else if(b.type==='toggle')inner=`<div class="toggle-title-row"><button class="toggle-chevron ${b.expanded?'open':''}" onclick="E._doToggleExpand('${b.id}')">▶</button><div class="toggle-title" data-bid="${b.id}" contenteditable="true" data-placeholder="${ph}" spellcheck="false">${mdEsc(b.content)}</div></div><div class="toggle-children" ${(b.expanded===false)?'style="display:none"':''}>${(b.children||[]).map((ch)=>renderNestedBlock(ch)).join('')}</div>`;
+      else if(b.type==='code')inner=`<div class="code-lang-label">${b.language||'Plain Text'}</div><pre><code data-bid="${b.id}" contenteditable="true" spellcheck="false">${mdEsc(b.content)}</code></pre>`;
+      else if(b.type==='callout')inner=`<span class="callout-icon" onclick="E._toggleCalloutIcon('${b.id}')" title="Change icon">${b.icon||'💡'}</span><div data-bid="${b.id}" contenteditable="true" data-placeholder="${ph}" spellcheck="false">${mdEsc(b.content)}</div><div class="callout-icon-picker" id="callout-picker-${b.id}" style="display:none">${CALLOUT_ICONS.map(function(i){return '<button type="button" class="callout-icon-opt" onclick="E._setCalloutIcon(\''+b.id+'\',\''+i+'\')">'+i+'</button>';}).join('')}</div>`;
+      else inner=`<div data-bid="${b.id}" contenteditable="true" data-placeholder="${ph}" spellcheck="false">${mdEsc(b.content)}</div>`;
       const tag=b.type.startsWith('heading_')?'h'+b.type.slice(-1):b.type==='quote'?'blockquote':'div';
       const cls=tag==='div'?`block-content ${b.type==='bulleted_list'?'block-bullet':b.type==='numbered_list'?'block-numbered':b.type==='to_do'?'block-todo':b.type==='toggle'?'block-toggle':b.type==='code'?'block-code':b.type==='callout'?'block-callout':''}`:`block-content block-${tag}`;
       const style=b.type==='callout'?` style="background:${(b.style&&b.style.bgColor)||'var(--blue-bg)'}"`:'';
@@ -695,12 +706,13 @@
           self.showToast('FlowDeck Agent : génération en cours…');
           window.fdAgent.ask(prompt);
         },
-        applyAIBlocks(text){
-          const lines=(text||'').split(/\r?\n/).map(function(s){return s.trim();}).filter(Boolean);
-          if(!lines.length) return;
+applyAIBlocks(text){
+          // Convert agent markdown → real blocks (headings, lists, tables, code…)
+          // so it renders naturally (Notion-style) instead of showing raw `## …`.
+          const nb=this.md2b(text||'');
+          if(!nb.length) return;
           this.sync();
           const startEmpty=this.blocks.length===1 && this.blocks[0].type==='paragraph' && !(this.blocks[0].content||'').trim();
-          const nb=lines.map(l=>this.mkB('paragraph',l));
           this.blocks = startEmpty ? nb : this.blocks.concat(nb);
           this.dirty=true; this.autoSave(); this.render();
         },