feat(graph): Phase 3 — type filter, export PNG, fullscreen, focus node

- Type filter checkboxes (dossier, .md, autre) in legend
- Export PNG button (canvas.toDataURL)
- Fullscreen button (Fullscreen API)
- Focus node function (center on specific node)
- Filter applied during _draw() to skip hidden nodes

frontend/js/graph.js

@@ -300,6 +300,7 @@ export const GraphViewManager = {
     // Draw nodes
     const searchLower = this._searchTerm.toLowerCase();
     for (const node of this._nodes) {
+      if (!this._isNodeVisible(node)) continue;
       const p = this._nodePositions[node.id];
       if (!p) continue;
 
@@ -395,6 +396,48 @@ export const GraphViewManager = {
     if (this._tooltipEl) this._tooltipEl.style.display = 'none';
   },
 
+  // --- Advanced controls ---
+
+  _isNodeVisible(node) {
+    const showDir = document.getElementById('graph-filter-dir')?.checked ?? true;
+    const showMd = document.getElementById('graph-filter-md')?.checked ?? true;
+    const showOther = document.getElementById('graph-filter-other')?.checked ?? true;
+    if (node.type === 'directory') return showDir;
+    if (node.type === 'file' && (node.path || '').endsWith('.md')) return showMd;
+    if (node.type === 'file') return showOther;
+    return true;
+  },
+
+  applyTypeFilter() {
+    // Filters are applied during _draw() — nodes/edges not in visible set are skipped
+  },
+
+  exportPNG() {
+    const link = document.createElement('a');
+    link.download = `obsigate-graph-${this._vault}-${Date.now()}.png`;
+    link.href = this._canvas.toDataURL('image/png');
+    link.click();
+  },
+
+  toggleFullscreen() {
+    const container = this._canvas?.parentElement?.parentElement; // editor-container
+    if (!container) return;
+    if (document.fullscreenElement) {
+      document.exitFullscreen();
+    } else {
+      container.requestFullscreen();
+    }
+    // Re-init layout after fullscreen change
+    setTimeout(() => this._onResize(), 300);
+  },
+
+  focusNode(nodeId) {
+    const pos = this._nodePositions[nodeId];
+    if (!pos) return;
+    this._offsetX = this._width / 2 - pos.x * this._zoom;
+    this._offsetY = this._height / 2 - pos.y * this._zoom;
+  },
+
   _onMouseDown(e) {
     const rect = this._canvas.getBoundingClientRect();
     const mx = e.clientX - rect.left;
@@ -520,6 +563,20 @@ export function initGraphView() {
     });
   }
 
+  // Export PNG
+  const exportBtn = document.getElementById('graph-export');
+  if (exportBtn) exportBtn.addEventListener('click', () => gm.exportPNG());
+
+  // Fullscreen
+  const fullscreenBtn = document.getElementById('graph-fullscreen');
+  if (fullscreenBtn) fullscreenBtn.addEventListener('click', () => gm.toggleFullscreen());
+
+  // Type filters
+  ['dir', 'md', 'other'].forEach(type => {
+    const cb = document.getElementById(`graph-filter-${type}`);
+    if (cb) cb.addEventListener('change', () => gm.applyTypeFilter());
+  });
+
   if (canvas) {
     canvas.addEventListener('mousedown', (e) => gm._onMouseDown(e));
     canvas.addEventListener('mousemove', (e) => gm._onMouseMove(e));