feat(graph): centered column headers + member avatar letters

- Column headers centered horizontally over pill area (not column edge)
- Member/lead nodes show first letter of name inside hexagon as avatar
  (bold, sized proportionally to node radius, colored in member color)
- Lead gets slightly smaller font (0.6r vs 0.7r) to fit context ring

packages/agent-graph/src/canvas/draw-agents.ts

@@ -44,6 +44,9 @@ export function drawAgents(
     // Hexagonal body with interior fill
     drawHexBody(ctx, x, y, r, color, node.state, time, isSelected, isHovered);
 
+    // Avatar: first letter of name centered inside hexagon
+    drawAvatar(ctx, x, y, r, node.label, color, node.kind === 'lead');
+
     // Breathing animation + spawn/waiting effects
     drawBreathing(ctx, x, y, r, node.state, time, node.spawnStatus);
 
@@ -207,6 +210,25 @@ function drawBreathing(
   }
 }
 
+function drawAvatar(
+  ctx: CanvasRenderingContext2D,
+  x: number,
+  y: number,
+  r: number,
+  name: string,
+  color: string,
+  isLead: boolean,
+): void {
+  const letter = name.charAt(0).toUpperCase();
+  const fontSize = isLead ? Math.round(r * 0.6) : Math.round(r * 0.7);
+
+  ctx.font = `bold ${fontSize}px sans-serif`;
+  ctx.textAlign = 'center';
+  ctx.textBaseline = 'middle';
+  ctx.fillStyle = hexWithAlpha(color, 0.9);
+  ctx.fillText(letter, x, y + 1);
+}
+
 function drawLabel(
   ctx: CanvasRenderingContext2D,
   x: number,

packages/agent-graph/src/layout/kanbanLayout.ts

@@ -8,7 +8,7 @@
  */
 
 import type { GraphNode } from '../ports/types';
-import { KANBAN_ZONE } from '../constants/canvas-constants';
+import { KANBAN_ZONE, TASK_PILL } from '../constants/canvas-constants';
 
 /** Column header info for rendering */
 export interface KanbanColumnHeader {
@@ -125,10 +125,10 @@ export class KanbanLayoutEngine {
       const colX = baseX + colIdx * columnWidth;
       const config = COLUMN_LABELS[col.name] ?? { label: col.name, color: '#888' };
 
-      // Column header
+      // Column header — centered over pill area
       headers.push({
         label: config.label,
-        x: colX + columnWidth / 2, // centered in column
+        x: colX + TASK_PILL.width / 2, // horizontally centered over pills
         y: baseY,
         color: config.color,
       });