feat(weak): aplt plotters for WeakDataset shear catalogues (#496)

[Jammy2211]

Summary

Add a new autolens/weak/plot/ package providing module-level matplotlib helpers for visualising a WeakDataset — the data class added in step 1 of the weak-lensing series (PR #473). All five helpers are re-exported into the aplt namespace so workspace scripts can call e.g. aplt.subplot_weak_dataset(dataset=...).

Closes step 2 of the weak-lensing roadmap (issue #496). The workspace TODO placeholders in autolens_workspace/scripts/weak/simulator.py will be filled in by a follow-up workspace PR once this lands.

API Changes

Pure additions — no removals, no signature changes. Five new public functions on the aplt namespace for weak-lensing shear-catalogue visualisation. See full details below.

Test Plan

• pytest test_autolens/weak/ -v → 16 passed (5 new plotter + 11 existing dataset/simulator)
• python -c "import autolens.plot as aplt; aplt.subplot_weak_dataset" → resolves without ImportError
• grep "^import jax\|^from jax" autolens/weak/plot/*.py → empty (numpy-only plotters)

Full API Changes (for automation & release notes)

Added

New module autolens.weak.plot.weak_dataset_plots:

• plot_shear_yx_2d(shear_yx, ax=None, title="Shear Field", output_path=None, output_filename="shear_yx", output_format=None) — single-panel headless-quiver of a shear field at galaxy positions, colour-coded by |γ|. Uses pivot="middle", headwidth=0, headlength=0, headaxislength=0 (spin-2 convention).
• plot_ellipticities(shear_yx, ax=None, title=r"Shear Magnitude $|\gamma|$", output_path=None, output_filename="shear_ellipticities", output_format=None) — scalar-coloured scatter of |γ| via autoarray.plot.grid.plot_grid.
• plot_phis(shear_yx, ax=None, title=r"Shear Position Angle $\phi$", output_path=None, output_filename="shear_phis", output_format=None) — scalar-coloured scatter of position angle with cyclic colormap.
• plot_noise_map(dataset, ax=None, title="Noise Map", output_path=None, output_filename="noise_map", output_format=None) — scalar-coloured scatter of per-galaxy shear noise.
• subplot_weak_dataset(dataset, output_path=None, output_filename="subplot_weak_dataset", output_format=None, title_prefix=None) — 2×2 mosaic combining the four single-panel helpers.

All five re-exported into autolens.plot (the aplt namespace).

Migration

None required — additive change.

Implementation notes

• Plotters access the shear field exclusively through .ellipticities (|γ|) and .phis (degrees, converted to radians inside plot_shear_yx_2d via np.deg2rad). The [:,0]=γ₂, [:,1]=γ₁ storage convention pinned by PyAutoGalaxy PR Jax to Main!  #366 stays encapsulated.
• Pure numpy — no JAX imports.
• Tests use direct module imports (from autolens.weak.plot.weak_dataset_plots import ...) matching the pattern in test_autolens/point/plot/.

🤖 Generated with Claude Code

[Jammy2211]

Workspace follow-up PR: PyAutoLabs/autolens_workspace#186