Fix share label group overrides

[cvanelteren]

Fix share‑label group precedence so explicit groups are the sole source of spanning labels and avoid mis‑anchored labels when mixed layouts are used, while also clearing share‑label groups on full‑grid axs.format(xlabel=...) to make global overrides deterministic; add regression tests covering subgroup labels vs global overrides.

import numpy as np

import ultraplot as uplt

rng = np.random.default_rng(21)
x = np.linspace(0, 5, 300)

layout = [[1, 2, 5], [3, 4, 5]]
# layout = [[1, 2], [4, 4]]
fig, axs = uplt.subplots(layout, journal="nat1")
for i, ax in enumerate(axs):
    trend = (i + 1) * 0.2
    y = np.exp(-0.4 * x) * np.sin(2 * x + i * 0.6) + trend
    y += 0.05 * rng.standard_normal(x.size)
    ax.plot(x, y, lw=2)
    ax.fill_between(x, y - 0.15, y + 0.15, alpha=0.2)
    ax.set_title(f"Condition {i + 1}")
# Share first 2 plots top left
axs[:2].format(
    xlabel="Time (days)",
)
axs[1, :2].format(xlabel="Time 2 (days)")
axs[[-1]].format(xlabel="Time 3 (days)")
axs.format(
    ylabel="Normalized response",
    abc=True,
    abcloc="ul",
    suptitle="Spanning labels with shared axes",
    grid=False,
)
axs.format(abc=1, abcloc="ol")

[codecov]

Codecov Report

❌ Patch coverage is 85.71429% with 6 lines in your changes missing coverage. Please review.

Files with missing lines	Patch %	Lines
ultraplot/figure.py	64.70%	3 Missing and 3 partials ⚠️

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