feat(matplotlib): implement errorbar-basic (#5382)

## Implementation: `errorbar-basic` - python/matplotlib

Implements the **python/matplotlib** version of `errorbar-basic`.

**File:** `plots/errorbar-basic/implementations/python/matplotlib.py`

**Parent Issue:** #973

---
:robot: *[impl-generate
workflow](https://github.com/MarkusNeusinger/anyplot/actions/runs/24926861415)*

---------

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

Author: github-actions[bot]

plots/errorbar-basic/implementations/python/matplotlib.py

@@ -1,52 +1,66 @@
-""" pyplots.ai
+""" anyplot.ai
 errorbar-basic: Basic Error Bar Plot
-Library: matplotlib 3.10.8 | Python 3.13.11
-Quality: 92/100 | Created: 2025-12-23
+Library: matplotlib 3.10.9 | Python 3.14.4
+Quality: 86/100 | Updated: 2026-04-25
 """
 
+import os
+
 import matplotlib.pyplot as plt
 import numpy as np
 
 
+# Theme tokens
+THEME = os.getenv("ANYPLOT_THEME", "light")
+PAGE_BG = "#FAF8F1" if THEME == "light" else "#1A1A17"
+INK = "#1A1A17" if THEME == "light" else "#F0EFE8"
+INK_SOFT = "#4A4A44" if THEME == "light" else "#B8B7B0"
+BRAND = "#009E73"  # Okabe-Ito position 1
+
 # Data - experimental measurements with associated uncertainties
 np.random.seed(42)
 categories = ["Control", "Treatment A", "Treatment B", "Treatment C", "Treatment D", "Treatment E"]
 x = np.arange(len(categories))
-y = np.array([25.3, 38.7, 42.1, 35.8, 48.2, 31.5])  # Mean values
+y = np.array([25.3, 38.7, 42.1, 35.8, 48.2, 31.5])
 
 # Asymmetric errors: Treatment C and D have notably different lower/upper bounds
 asymmetric_lower = np.array([2.1, 3.5, 2.8, 6.5, 4.8, 2.5])
 asymmetric_upper = np.array([2.1, 3.5, 2.8, 2.8, 2.2, 2.5])
 
 # Plot
-fig, ax = plt.subplots(figsize=(16, 9))
+fig, ax = plt.subplots(figsize=(16, 9), facecolor=PAGE_BG)
+ax.set_facecolor(PAGE_BG)
 
-# Error bars with caps
 ax.errorbar(
     x,
     y,
     yerr=[asymmetric_lower, asymmetric_upper],
     fmt="o",
     markersize=15,
-    color="#306998",
-    ecolor="#306998",
+    color=BRAND,
+    ecolor=BRAND,
     elinewidth=3,
     capsize=10,
     capthick=3,
-    alpha=0.9,
+    markeredgecolor=PAGE_BG,
+    markeredgewidth=1.2,
+    alpha=0.95,
 )
 
-# Styling
-ax.set_xlabel("Experimental Group", fontsize=20)
-ax.set_ylabel("Response Value (units)", fontsize=20)
-ax.set_title("errorbar-basic · matplotlib · pyplots.ai", fontsize=24)
+# Style
+ax.set_xlabel("Experimental Group", fontsize=20, color=INK)
+ax.set_ylabel("Response Value (units)", fontsize=20, color=INK)
+ax.set_title("errorbar-basic · matplotlib · anyplot.ai", fontsize=24, fontweight="medium", color=INK)
 ax.set_xticks(x)
-ax.set_xticklabels(categories, fontsize=16)
-ax.tick_params(axis="y", labelsize=16)
-ax.grid(True, alpha=0.3, linestyle="--", axis="y")
-
-# Add some vertical padding
+ax.set_xticklabels(categories)
+ax.tick_params(axis="both", labelsize=16, colors=INK_SOFT)
+ax.spines["top"].set_visible(False)
+ax.spines["right"].set_visible(False)
+for s in ("left", "bottom"):
+    ax.spines[s].set_color(INK_SOFT)
+ax.yaxis.grid(True, alpha=0.10, linewidth=0.8, color=INK)
+ax.set_axisbelow(True)
 ax.set_ylim(0, max(y + asymmetric_upper) * 1.15)
 
 plt.tight_layout()
-plt.savefig("plot.png", dpi=300, bbox_inches="tight")
+plt.savefig(f"plot-{THEME}.png", dpi=300, bbox_inches="tight", facecolor=PAGE_BG)