Add gap-free topology documentation and plot_topology() convenience helper

[Copilot]

Plotting individual boundary types (plot_ridges, plot_transforms, plot_trenches) in isolation leaves visible gaps along "other connection" segments. The fix is to render plot_all_topological_sections() as a continuous backbone first, then layer the styled boundaries on top — a pattern used across the tutorial suite but undiscovered by most users.

Changes

Documentation

• Added a .. note:: block to get_ridges, plot_ridges, get_trenches, plot_trenches, get_transforms, and plot_transforms explaining:
  • why gaps appear
  • the backbone-first rendering pattern
  • reference to the new plot_topology() helper

New PlotTopologies.plot_topology() helper

Convenience method that enforces correct draw order internally: backbone → ridges → transforms → trenches.

# One-call gap-free topology with defaults (grey backbone, red ridges, black trenches)
gplot.plot_topology(ax)

# Fully customised
gplot.plot_topology(
    ax,
    backbone_kwargs={"color": "lightgrey", "linewidth": 0.5},
    ridge_kwargs={"color": "red", "linewidth": 1},
    transform_kwargs={"color": "green"},
    trench_kwargs={"color": "blue"},
)

# Skip a layer by passing False
gplot.plot_topology(ax, transform_kwargs=False, ridge_kwargs=False)

Parameter semantics: None → draw with default style; dict → draw with custom kwargs; False → skip layer. Transforms are skipped (False) by default since they visually overlap with ridges.

Tests

Added test_plot_topology_adds_artists and test_plot_topology_skip_layer to test_3_plottopologies.py.