feat(chartjs): implement venn-labeled-items (#9508)

## Implementation: `venn-labeled-items` - javascript/chartjs

Implements the **javascript/chartjs** version of `venn-labeled-items`.

**File:**
`plots/venn-labeled-items/implementations/javascript/chartjs.js`

**Parent Issue:** #5364

---
:robot: *[impl-generate
workflow](https://github.com/MarkusNeusinger/anyplot/actions/runs/28167044348)*

---------

Co-authored-by: github-actions[bot] <github-actions[bot]@users.noreply.github.com>
Co-authored-by: claude[bot] <41898282+claude[bot]@users.noreply.github.com>
Co-authored-by: Markus Neusinger <2921697+MarkusNeusinger@users.noreply.github.com>

Author: github-actions[bot]

plots/venn-labeled-items/implementations/javascript/chartjs.js

@@ -0,0 +1,168 @@
+// anyplot.ai
+// venn-labeled-items: Chartgeist-Style Venn Diagram with Labeled Items
+// Library: chartjs 4.4.7 | JavaScript 22.23.0
+// Quality: 85/100 | Created: 2026-06-25
+
+const t = window.ANYPLOT_TOKENS;
+
+// --- Data ------------------------------------------------------------------
+const circles = [
+  { name: "Hyped Online",     color: t.palette[0] },  // #009E73 — Imprint palette pos 1
+  { name: "Actually Useful",  color: t.palette[1] },  // #C475FD — Imprint palette pos 2
+  { name: "Secretly Beloved", color: t.palette[2] },  // #4467A3 — Imprint palette pos 3
+];
+
+const items = [
+  { label: "NFTs",           zone: "A"   },
+  { label: "Metaverse",      zone: "A"   },
+  { label: "Spreadsheets",   zone: "B"   },
+  { label: "Google Maps",    zone: "B"   },
+  { label: "RSS Feeds",      zone: "C"   },
+  { label: "Fax Machines",   zone: "C"   },
+  { label: "ChatGPT",        zone: "AB"  },
+  { label: "Slack",          zone: "AB"  },
+  { label: "TikTok",         zone: "AC"  },
+  { label: "Vinyl Records",  zone: "AC"  },
+  { label: "Wikipedia",      zone: "BC"  },
+  { label: "Duct Tape",      zone: "BC"  },
+  { label: "The Internet",   zone: "ABC" },
+  { label: "Coffee",         zone: "ABC" },
+];
+
+// --- Mount -----------------------------------------------------------------
+const canvas = document.createElement("canvas");
+document.getElementById("container").appendChild(canvas);
+
+// --- Venn drawing plugin ---------------------------------------------------
+const vennPlugin = {
+  id: "vennLabeled",
+  afterDraw(chart) {
+    const ctx = chart.ctx;
+    const W = chart.width;
+    const H = chart.height;
+
+    // Background
+    ctx.fillStyle = t.pageBg;
+    ctx.fillRect(0, 0, W, H);
+
+    // Layout geometry
+    const cx = W * 0.5;
+    const cy = H * 0.50;
+    const r  = Math.min(W, H) * 0.32;
+    const d  = r * 0.58;
+
+    // Circle centers — equilateral-triangle arrangement
+    const A = { x: cx - d * Math.cos(Math.PI / 6), y: cy - d * 0.55 };
+    const B = { x: cx + d * Math.cos(Math.PI / 6), y: cy - d * 0.55 };
+    const C = { x: cx,                               y: cy + d * 0.80 };
+    const ctrs = [A, B, C];
+
+    // Semi-transparent circle fills
+    for (let i = 0; i < 3; i++) {
+      ctx.save();
+      ctx.globalAlpha = 0.21;
+      ctx.beginPath();
+      ctx.arc(ctrs[i].x, ctrs[i].y, r, 0, 2 * Math.PI);
+      ctx.fillStyle = circles[i].color;
+      ctx.fill();
+      ctx.restore();
+    }
+
+    // Circle outlines
+    for (let i = 0; i < 3; i++) {
+      ctx.save();
+      ctx.globalAlpha = 0.60;
+      ctx.beginPath();
+      ctx.arc(ctrs[i].x, ctrs[i].y, r, 0, 2 * Math.PI);
+      ctx.strokeStyle = circles[i].color;
+      ctx.lineWidth = 2.5;
+      ctx.stroke();
+      ctx.restore();
+    }
+
+    // Zone centers — verified to lie inside the correct regions
+    const z = {
+      A:   { x: A.x - r * 0.50, y: A.y - r * 0.20 },
+      B:   { x: B.x + r * 0.50, y: B.y - r * 0.20 },
+      C:   { x: cx,              y: C.y + r * 0.40  },
+      AB:  { x: cx,              y: cy - d * 1.10   },
+      AC:  { x: cx - d * 0.75,  y: cy + d * 0.30   },
+      BC:  { x: cx + d * 0.75,  y: cy + d * 0.30   },
+      ABC: { x: cx,              y: cy              },
+    };
+
+    // Category name labels (outside each circle)
+    const catFontSize = Math.round(r * 0.13);
+    ctx.font = `bold ${catFontSize}px Georgia, serif`;
+    ctx.textBaseline = "middle";
+    const catPos = [
+      { x: A.x - r * 0.95, y: A.y - r * 0.68, align: "center" },
+      { x: B.x + r * 0.95, y: B.y - r * 0.68, align: "center" },
+      { x: cx,              y: C.y + r * 1.05,  align: "center" },
+    ];
+    for (let i = 0; i < 3; i++) {
+      ctx.fillStyle = circles[i].color;
+      ctx.textAlign = catPos[i].align;
+      ctx.fillText(circles[i].name, catPos[i].x, catPos[i].y);
+    }
+
+    // Group items by zone
+    const byZone = {};
+    for (const item of items) {
+      (byZone[item.zone] = byZone[item.zone] || []).push(item.label);
+    }
+
+    // Item labels inside each zone
+    const itemFontSize = Math.round(r * 0.095);
+    const lineH = itemFontSize * 1.65;
+    ctx.font = `${itemFontSize}px Georgia, serif`;
+    ctx.textAlign = "center";
+    ctx.textBaseline = "middle";
+    ctx.fillStyle = t.inkSoft;
+
+    for (const [zone, labels] of Object.entries(byZone)) {
+      const base = z[zone];
+      if (!base) continue;
+      const startY = base.y - ((labels.length - 1) * lineH) / 2;
+      for (let i = 0; i < labels.length; i++) {
+        ctx.fillText(labels[i], base.x, startY + i * lineH);
+      }
+    }
+
+    // Title (scaled for length)
+    const titleText = "Tech Zeitgeist · venn-labeled-items · javascript · chartjs · anyplot.ai";
+    const titleSize = Math.max(12, Math.round(22 * 67 / titleText.length));
+    ctx.font = `bold ${titleSize}px Georgia, serif`;
+    ctx.fillStyle = t.ink;
+    ctx.textAlign = "center";
+    ctx.textBaseline = "top";
+    ctx.fillText(titleText, W / 2, H * 0.022);
+
+    // Subtitle
+    const subtitleSize = Math.max(10, Math.round(titleSize * 0.72));
+    ctx.font = `italic ${subtitleSize}px Georgia, serif`;
+    ctx.fillStyle = t.inkSoft;
+    ctx.fillText("Where does it live — hype, utility, or quiet devotion?", W / 2, H * 0.022 + titleSize * 1.5);
+  },
+};
+
+// --- Chart (blank scatter used as canvas container + custom Venn plugin) ---
+new Chart(canvas, {
+  type: "scatter",
+  data: { datasets: [] },
+  options: {
+    responsive: true,
+    maintainAspectRatio: false,
+    animation: false,
+    layout: { padding: 0 },
+    plugins: {
+      legend: { display: false },
+      title:  { display: false },
+    },
+    scales: {
+      x: { display: false },
+      y: { display: false },
+    },
+  },
+  plugins: [vennPlugin],
+});