feat(letsplot): implement waffle-basic (#1050)

## Implementation: `waffle-basic` - letsplot

Implements the **letsplot** version of `waffle-basic`.

**File:** `plots/waffle-basic/implementations/letsplot.py`

**Parent Issue:** #998

---
:robot: *[impl-generate
workflow](https://github.com/MarkusNeusinger/pyplots/actions/runs/20260266028)*

---------

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Co-authored-by: github-actions[bot] <41898282+github-actions[bot]@users.noreply.github.com>

Author: github-actions[bot]

plots/waffle-basic/implementations/letsplot.py

@@ -0,0 +1,79 @@
+"""
+waffle-basic: Basic Waffle Chart
+Library: letsplot
+"""
+
+import pandas as pd
+from lets_plot import (
+    LetsPlot,
+    aes,
+    coord_fixed,
+    element_blank,
+    element_text,
+    geom_tile,
+    ggplot,
+    ggsize,
+    labs,
+    scale_fill_manual,
+    theme,
+    theme_void,
+)
+from lets_plot.export import ggsave
+
+
+LetsPlot.setup_html()
+
+# Data - Market share by category (values sum to 100%)
+categories = ["Product A", "Product B", "Product C", "Product D"]
+values = [42, 28, 18, 12]  # Percentages
+
+# Colors - Python Blue first, then colorblind-safe palette
+colors = ["#306998", "#FFD43B", "#4CAF50", "#FF7043"]
+
+# Build 10x10 waffle grid (100 squares, each = 1%)
+# Fill from top-left, row by row
+grid_data = []
+square_idx = 0
+
+for cat, val in zip(categories, values, strict=True):
+    for _ in range(val):
+        row = 9 - (square_idx // 10)  # Start from top (row 9) going down
+        col = square_idx % 10
+        grid_data.append({"x": col, "y": row, "category": cat})
+        square_idx += 1
+
+df = pd.DataFrame(grid_data)
+
+# Preserve category order for legend
+df["category"] = pd.Categorical(df["category"], categories=categories, ordered=True)
+
+# Create legend labels with percentages
+legend_labels = {cat: f"{cat} ({val}%)" for cat, val in zip(categories, values, strict=True)}
+df["legend_label"] = df["category"].map(legend_labels)
+df["legend_label"] = pd.Categorical(
+    df["legend_label"], categories=[legend_labels[cat] for cat in categories], ordered=True
+)
+
+# Plot
+plot = (
+    ggplot(df, aes(x="x", y="y", fill="legend_label"))
+    + geom_tile(width=0.9, height=0.9, size=0)
+    + coord_fixed(ratio=1)
+    + scale_fill_manual(values=colors)
+    + labs(title="waffle-basic · letsplot · pyplots.ai", fill="Category")
+    + theme_void()
+    + theme(
+        plot_title=element_text(size=24, hjust=0.5),
+        legend_title=element_text(size=18),
+        legend_text=element_text(size=16),
+        axis_title=element_blank(),
+        axis_text=element_blank(),
+    )
+    + ggsize(1600, 900)
+)
+
+# Save PNG (scale=3 gives 4800x2700)
+ggsave(plot, "plot.png", path=".", scale=3)
+
+# Save HTML for interactivity
+ggsave(plot, "plot.html", path=".")

plots/waffle-basic/metadata/letsplot.yaml

@@ -0,0 +1,23 @@
+# Per-library metadata for letsplot implementation of waffle-basic
+# Auto-generated by impl-generate.yml
+
+library: letsplot
+specification_id: waffle-basic
+
+# Preview URLs (filled by workflow)
+preview_url: https://storage.googleapis.com/pyplots-images/plots/waffle-basic/letsplot/plot.png
+preview_thumb: https://storage.googleapis.com/pyplots-images/plots/waffle-basic/letsplot/plot_thumb.png
+preview_html: https://storage.googleapis.com/pyplots-images/plots/waffle-basic/letsplot/plot.html
+
+current:
+  version: 0
+  generated_at: 2025-12-16T07:46:50Z
+  generated_by: claude-opus-4-5-20251101
+  workflow_run: 20260266028
+  issue: 998
+  quality_score: 95
+  # Version info (filled by workflow)
+  python_version: "3.13.11"
+  library_version: "unknown"
+
+history: []