feat(letsplot): implement point-basic (#2589)

## Implementation: `point-basic` - letsplot

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

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

---
:robot: *[impl-generate
workflow](https://github.com/MarkusNeusinger/pyplots/actions/runs/20593353470)*

---------

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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/letsplot.py

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+""" pyplots.ai
+point-basic: Point Estimate Plot
+Library: letsplot 4.8.2 | Python 3.13.11
+Quality: 92/100 | Created: 2025-12-30
+"""
+
+import numpy as np
+import pandas as pd
+from lets_plot import *
+
+
+LetsPlot.setup_html()
+
+# Data - Research study results with confidence intervals
+np.random.seed(42)
+categories = ["Treatment A", "Treatment B", "Treatment C", "Control", "Placebo"]
+estimates = [4.2, 5.8, 3.1, 2.5, 1.8]
+# Generate realistic confidence intervals (narrower for larger effects)
+ci_width = [0.9, 1.1, 0.7, 0.8, 0.6]
+lower = [e - w for e, w in zip(estimates, ci_width)]
+upper = [e + w for e, w in zip(estimates, ci_width)]
+
+df = pd.DataFrame({"group": categories, "estimate": estimates, "lower": lower, "upper": upper})
+
+# Plot - Horizontal point estimate plot with confidence intervals
+plot = (
+    ggplot(df, aes(x="group", y="estimate", ymin="lower", ymax="upper"))
+    + geom_pointrange(color="#306998", size=1.5, linewidth=1.5)
+    + geom_hline(yintercept=0, linetype="dashed", color="#666666", size=0.8, alpha=0.7)
+    + labs(y="Effect Size (95% CI)", x="Treatment Group", title="point-basic · lets-plot · pyplots.ai")
+    + coord_flip()
+    + theme_minimal()
+    + theme(
+        plot_title=element_text(size=24, face="bold"),
+        axis_title=element_text(size=20),
+        axis_text=element_text(size=16),
+        panel_grid_major_x=element_blank(),
+        panel_grid_minor=element_blank(),
+    )
+    + ggsize(1600, 900)
+)
+
+# Save
+ggsave(plot, "plot.png", path=".", scale=3)
+
+# Save interactive HTML
+ggsave(plot, "plot.html", path=".")

plots/point-basic/metadata/letsplot.yaml

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+library: letsplot
+specification_id: point-basic
+created: '2025-12-30T09:34:53Z'
+updated: '2025-12-30T09:44:43Z'
+generated_by: claude-opus-4-5-20251101
+workflow_run: 20593353470
+issue: 0
+python_version: 3.13.11
+library_version: 4.8.2
+preview_url: https://storage.googleapis.com/pyplots-images/plots/point-basic/letsplot/plot.png
+preview_thumb: https://storage.googleapis.com/pyplots-images/plots/point-basic/letsplot/plot_thumb.png
+preview_html: https://storage.googleapis.com/pyplots-images/plots/point-basic/letsplot/plot.html
+quality_score: 92
+review:
+  strengths:
+  - Excellent use of geom_pointrange for clean point-and-interval visualization
+  - Proper horizontal orientation with coord_flip for readable category labels
+  - Reference line at zero helps interpretation of effect sizes
+  - Clean minimal theme with appropriate font sizes for the 4800x2700 output
+  - Realistic clinical trial scenario with varying confidence interval widths
+  weaknesses:
+  - All effect sizes are positive; including at least one negative or zero-crossing
+    effect would better demonstrate the plot utility
+  - Does not include error bar caps at endpoints (spec suggests caps)