feat(plotly): implement violin-box (#2677)

## Implementation: `violin-box` - plotly

Implements the **plotly** version of `violin-box`.

**File:** `plots/violin-box/implementations/plotly.py`

---
:robot: *[impl-generate
workflow](https://github.com/MarkusNeusinger/pyplots/actions/runs/20595336413)*

---------

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

Author: github-actions[bot]

plots/violin-box/implementations/plotly.py

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+""" pyplots.ai
+violin-box: Violin Plot with Embedded Box Plot
+Library: plotly 6.5.0 | Python 3.13.11
+Quality: 92/100 | Created: 2025-12-30
+"""
+
+import numpy as np
+import plotly.graph_objects as go
+
+
+# Data - Test scores across different teaching methods
+np.random.seed(42)
+
+# Generate realistic test score distributions for 4 teaching methods
+groups = ["Traditional", "Interactive", "Online", "Hybrid"]
+data = {
+    "Traditional": np.random.normal(70, 12, 80),  # Centered around 70
+    "Interactive": np.random.normal(78, 10, 85),  # Higher scores, tighter
+    "Online": np.concatenate(
+        [  # Bimodal distribution
+            np.random.normal(55, 8, 40),
+            np.random.normal(80, 7, 45),
+        ]
+    ),
+    "Hybrid": np.random.normal(75, 15, 90),  # More spread
+}
+
+# Clip to realistic test score range (0-100)
+for group in groups:
+    data[group] = np.clip(data[group], 0, 100)
+
+# Colors - Python palette + accessible colors
+colors = ["#306998", "#FFD43B", "#4B8BBE", "#E377C2"]
+
+# Create figure
+fig = go.Figure()
+
+# Add violin with embedded box plot for each group
+for i, group in enumerate(groups):
+    fig.add_trace(
+        go.Violin(
+            y=data[group],
+            name=group,
+            box_visible=True,  # Show box plot inside
+            meanline_visible=True,  # Show mean line
+            fillcolor=colors[i],
+            opacity=0.7,
+            line={"color": "black", "width": 1.5},
+            points="outliers",  # Show outliers
+            pointpos=0,
+            marker={"size": 8, "color": "black", "opacity": 0.7},
+            box={"fillcolor": "white", "line": {"color": "black", "width": 2}, "width": 0.15},
+            meanline={"color": "darkred", "width": 2},
+        )
+    )
+
+# Layout for 4800x2700 px output
+fig.update_layout(
+    title={
+        "text": "violin-box · plotly · pyplots.ai",
+        "font": {"size": 32, "color": "black"},
+        "x": 0.5,
+        "xanchor": "center",
+    },
+    xaxis={"title": {"text": "Teaching Method", "font": {"size": 24}}, "tickfont": {"size": 20}, "showgrid": False},
+    yaxis={
+        "title": {"text": "Test Score (points)", "font": {"size": 24}},
+        "tickfont": {"size": 20},
+        "gridcolor": "rgba(0,0,0,0.1)",
+        "gridwidth": 1,
+        "range": [0, 105],
+    },
+    template="plotly_white",
+    showlegend=False,
+    plot_bgcolor="white",
+    paper_bgcolor="white",
+    margin={"l": 100, "r": 50, "t": 100, "b": 100},
+    violingap=0.3,
+    violinmode="group",
+)
+
+# Save as PNG (4800 x 2700 px)
+fig.write_image("plot.png", width=1600, height=900, scale=3)
+
+# Save interactive HTML
+fig.write_html("plot.html", include_plotlyjs="cdn")

plots/violin-box/metadata/plotly.yaml

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+library: plotly
+specification_id: violin-box
+created: '2025-12-30T11:23:43Z'
+updated: '2025-12-30T11:36:23Z'
+generated_by: claude-opus-4-5-20251101
+workflow_run: 20595336413
+issue: 0
+python_version: 3.13.11
+library_version: 6.5.0
+preview_url: https://storage.googleapis.com/pyplots-images/plots/violin-box/plotly/plot.png
+preview_thumb: https://storage.googleapis.com/pyplots-images/plots/violin-box/plotly/plot_thumb.png
+preview_html: https://storage.googleapis.com/pyplots-images/plots/violin-box/plotly/plot.html
+quality_score: 92
+review:
+  strengths:
+  - Excellent demonstration of bimodal distribution in Online group showcasing violin
+    plot capability
+  - Clean embedded box plots with visible median, quartiles, and whiskers
+  - Mean lines (red) add extra statistical information beyond spec requirements
+  - Realistic education scenario with plausible test score distributions
+  - Proper output sizing (4800x2700) with readable fonts
+  - Both PNG and interactive HTML outputs provided
+  weaknesses:
+  - Grid alpha at 0.1 makes gridlines very faint; could use 0.2-0.3 for better readability
+  - Outlier markers are small (size 8); increasing to 10-12 would improve visibility
+  - Yellow color for Interactive group may have reduced contrast for some colorblind
+    users