feat(matplotlib): implement area-mountain-panorama (#5368)

## Implementation: `area-mountain-panorama` - python/matplotlib

Implements the **python/matplotlib** version of
`area-mountain-panorama`.

**File:**
`plots/area-mountain-panorama/implementations/python/matplotlib.py`

**Parent Issue:** #5365

---
:robot: *[impl-generate
workflow](https://github.com/MarkusNeusinger/anyplot/actions/runs/24918592166)*

---------

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

Author: github-actions[bot]

plots/area-mountain-panorama/implementations/python/matplotlib.py

@@ -0,0 +1,145 @@
+""" anyplot.ai
+area-mountain-panorama: Mountain Panorama Profile with Labeled Peaks
+Library: matplotlib 3.10.9 | Python 3.14.4
+Quality: 91/100 | Created: 2026-04-25
+"""
+
+import os
+
+import matplotlib.pyplot as plt
+import numpy as np
+from matplotlib.colors import LinearSegmentedColormap
+
+
+# Theme tokens
+THEME = os.getenv("ANYPLOT_THEME", "light")
+PAGE_BG = "#FAF8F1" if THEME == "light" else "#1A1A17"
+ELEVATED_BG = "#FFFDF6" if THEME == "light" else "#242420"
+INK = "#1A1A17" if THEME == "light" else "#F0EFE8"
+INK_SOFT = "#4A4A44" if THEME == "light" else "#B8B7B0"
+INK_MUTED = "#6B6A63" if THEME == "light" else "#A8A79F"
+BRAND = "#009E73"
+SKY_TOP = "#E8C8A0" if THEME == "light" else "#252D40"
+
+# Data — Wallis (Valais) summit panorama, ordered W → E
+peaks = [
+    ("Weisshorn", 12, 4506),
+    ("Zinalrothorn", 30, 4221),
+    ("Ober Gabelhorn", 45, 4063),
+    ("Dent Blanche", 58, 4358),
+    ("Dent d'Hérens", 76, 4171),
+    ("Matterhorn", 92, 4478),
+    ("Breithorn", 120, 4164),
+    ("Pollux", 132, 4092),
+    ("Castor", 139, 4223),
+    ("Liskamm", 152, 4527),
+    ("Monte Rosa", 170, 4634),
+    ("Strahlhorn", 192, 4190),
+    ("Rimpfischhorn", 204, 4199),
+    ("Allalinhorn", 215, 4027),
+    ("Alphubel", 225, 4206),
+    ("Täschhorn", 236, 4491),
+    ("Dom", 250, 4545),
+]
+
+# Skyline construction
+np.random.seed(42)
+angle = np.linspace(0, 262, 2000)
+
+# Base ridge: smoothed random walk in the 3000–3700 m belt (foothills + minor cols)
+walk = np.cumsum(np.random.randn(len(angle)) * 1.5)
+sigma_walk = 22
+g = np.arange(-3 * sigma_walk, 3 * sigma_walk + 1)
+kernel_walk = np.exp(-(g**2) / (2 * sigma_walk**2))
+walk = np.convolve(walk, kernel_walk / kernel_walk.sum(), mode="same")
+walk = (walk - walk.min()) / (walk.max() - walk.min())
+ridge = 3000 + walk * 700
+
+# Major summits as Gaussian peaks (max-combined for the visible silhouette)
+for _, pos, elev in peaks:
+    width = 5.5 + (elev - 4000) / 130
+    bump = (elev - 2700) * np.exp(-((angle - pos) ** 2) / (2 * width**2))
+    ridge = np.maximum(ridge, 2700 + bump)
+
+# Light final smoothing of the combined ridge
+sigma_ridge = 0.8
+g = np.arange(-3, 4)
+kernel_ridge = np.exp(-(g**2) / (2 * sigma_ridge**2))
+ridge = np.convolve(ridge, kernel_ridge / kernel_ridge.sum(), mode="same")
+
+# Plot
+fig, ax = plt.subplots(figsize=(16, 9), facecolor=PAGE_BG)
+ax.set_facecolor(PAGE_BG)
+
+# Sky gradient above ridgeline (dusk mood: warm peach for light, deep navy for dark)
+sky_cmap = LinearSegmentedColormap.from_list("sky", [PAGE_BG, SKY_TOP])
+sky_gradient = np.linspace(0, 1, 256).reshape(-1, 1)
+ax.imshow(
+    sky_gradient,
+    extent=(0, 262, 2400, 6050),
+    aspect="auto",
+    cmap=sky_cmap,
+    origin="lower",
+    zorder=1,
+    interpolation="bilinear",
+)
+
+# Mountain silhouette (covers the lower portion of the gradient — sky stays above ridge)
+ax.fill_between(angle, 2400, ridge, color=BRAND, linewidth=0, zorder=2)
+ax.plot(angle, ridge, color=BRAND, linewidth=1.0, zorder=3)
+
+# Peak labels staggered across three vertical levels, with thin leader lines
+label_levels = [5050, 5320, 5590]
+sorted_peaks = sorted(peaks, key=lambda p: p[1])
+for i, (name, pos, elev) in enumerate(sorted_peaks):
+    level = label_levels[i % 3]
+    is_anchor = name == "Matterhorn"
+    text_color = INK if is_anchor else INK_SOFT
+    text_weight = "bold" if is_anchor else "regular"
+    line_color = INK if is_anchor else INK_SOFT
+    line_alpha = 0.85 if is_anchor else 0.45
+    line_width = 1.4 if is_anchor else 0.8
+    fsize = 16 if is_anchor else 14
+
+    ax.plot([pos, pos], [elev + 25, level - 90], color=line_color, linewidth=line_width, alpha=line_alpha, zorder=4)
+    ax.text(
+        pos,
+        level,
+        f"{name}\n{elev:,} m",
+        ha="center",
+        va="bottom",
+        fontsize=fsize,
+        fontweight=text_weight,
+        color=text_color,
+        linespacing=1.35,
+        zorder=5,
+    )
+
+# Axes
+ax.set_ylim(2500, 6050)
+ax.set_xlim(0, 262)
+ax.set_ylabel("Elevation (m)", fontsize=20, color=INK)
+ax.set_title(
+    "Wallis Alps · area-mountain-panorama · matplotlib · anyplot.ai",
+    fontsize=24,
+    fontweight="medium",
+    color=INK,
+    pad=18,
+)
+
+# Compass bearings on x-axis
+compass_ticks = [10, 65, 120, 180, 245]
+compass_labels = ["W", "SW", "S", "SE", "E"]
+ax.set_xticks(compass_ticks)
+ax.set_xticklabels(compass_labels, fontsize=16, color=INK_SOFT)
+ax.tick_params(axis="x", colors=INK_SOFT, length=0)
+ax.tick_params(axis="y", 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)
+
+plt.tight_layout()
+plt.savefig(f"plot-{THEME}.png", dpi=300, bbox_inches="tight", facecolor=PAGE_BG)