feat(plotly): implement point-basic (#2574)

## Implementation: `point-basic` - plotly

Implements the **plotly** version of `point-basic`.

**File:** `plots/point-basic/implementations/plotly.py`

---
:robot: *[impl-generate
workflow](https://github.com/MarkusNeusinger/pyplots/actions/runs/20593348770)*

---------

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

Author: github-actions[bot]

plots/point-basic/implementations/plotly.py

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+""" pyplots.ai
+point-basic: Point Estimate 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 - Treatment effects for different interventions
+np.random.seed(42)
+categories = ["Control", "Treatment A", "Treatment B", "Treatment C", "Treatment D", "Treatment E"]
+
+# Generate realistic point estimates with varying confidence intervals
+estimates = [0.0, 2.3, 3.8, 1.5, 4.2, 2.9]
+# CI widths vary by sample size/variance
+ci_widths = [0.8, 1.2, 0.9, 1.5, 1.1, 1.3]
+lower = [e - w for e, w in zip(estimates, ci_widths, strict=False)]
+upper = [e + w for e, w in zip(estimates, ci_widths, strict=False)]
+
+# Create figure
+fig = go.Figure()
+
+# Add error bars (horizontal orientation)
+fig.add_trace(
+    go.Scatter(
+        x=estimates,
+        y=categories,
+        mode="markers",
+        marker={"size": 18, "color": "#306998", "symbol": "circle"},
+        error_x={
+            "type": "data",
+            "symmetric": False,
+            "array": [u - e for e, u in zip(estimates, upper, strict=False)],
+            "arrayminus": [e - low for e, low in zip(estimates, lower, strict=False)],
+            "color": "#306998",
+            "thickness": 3,
+            "width": 10,
+        },
+        name="Estimate ± 95% CI",
+        showlegend=True,
+    )
+)
+
+# Add reference line at zero (null hypothesis)
+fig.add_vline(
+    x=0,
+    line={"color": "#FFD43B", "width": 3, "dash": "dash"},
+    annotation_text="Null",
+    annotation_position="top",
+    annotation_font={"size": 18, "color": "#FFD43B"},
+)
+
+# Layout
+fig.update_layout(
+    title={"text": "point-basic · plotly · pyplots.ai", "font": {"size": 32}, "x": 0.5, "xanchor": "center"},
+    xaxis={
+        "title": {"text": "Effect Size (units)", "font": {"size": 24}},
+        "tickfont": {"size": 18},
+        "zeroline": False,
+        "gridcolor": "rgba(0,0,0,0.1)",
+        "gridwidth": 1,
+    },
+    yaxis={
+        "title": {"text": "Treatment Group", "font": {"size": 24}},
+        "tickfont": {"size": 20},
+        "gridcolor": "rgba(0,0,0,0.1)",
+        "gridwidth": 1,
+    },
+    template="plotly_white",
+    legend={
+        "font": {"size": 18},
+        "x": 0.98,
+        "y": 0.02,
+        "xanchor": "right",
+        "yanchor": "bottom",
+        "bgcolor": "rgba(255,255,255,0.8)",
+    },
+    margin={"l": 150, "r": 80, "t": 100, "b": 80},
+)
+
+# Save as PNG and HTML
+fig.write_image("plot.png", width=1600, height=900, scale=3)
+fig.write_html("plot.html", include_plotlyjs="cdn")

plots/point-basic/metadata/plotly.yaml

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+library: plotly
+specification_id: point-basic
+created: '2025-12-30T09:31:42Z'
+updated: '2025-12-30T09:42:21Z'
+generated_by: claude-opus-4-5-20251101
+workflow_run: 20593348770
+issue: 0
+python_version: 3.13.11
+library_version: 6.5.0
+preview_url: https://storage.googleapis.com/pyplots-images/plots/point-basic/plotly/plot.png
+preview_thumb: https://storage.googleapis.com/pyplots-images/plots/point-basic/plotly/plot_thumb.png
+preview_html: https://storage.googleapis.com/pyplots-images/plots/point-basic/plotly/plot.html
+quality_score: 92
+review:
+  strengths:
+  - Excellent horizontal orientation matching spec recommendation for readability
+  - Clear reference line at null hypothesis with annotation
+  - Well-sized markers (18) and error bars with visible caps (width=10)
+  - Proper use of asymmetric error bars calculated from CI bounds
+  - Clean clinical trial context that is realistic and neutral
+  - Good font sizing hierarchy (title 32, labels 24, ticks 18-20)
+  weaknesses:
+  - Legend positioned in bottom-right could overlap with data; top-right or outside
+    placement preferred
+  - All treatment effects are positive; including one negative effect would better
+    demonstrate full capability
+  - Grid opacity at 0.1 is very subtle; 0.2-0.3 would improve readability