feat: prior configs + docs for the AdaptPower regularization siblings

[Jammy2211]

Summary

Prior configs, API docs and a composition test for the four *Power regularization siblings added in PyAutoLabs/PyAutoArray#512 (AdaptPower, AdaptSplitPower, AdaptSplitZerothPower, MaternAdaptPowerKernel).

• autogalaxy/config/priors/regularization/{adapt_power,adapt_split_power,adapt_split_zeroth_power,matern_adapt_power_kernel}.yaml are copies of their legacy counterparts — same LogUniform(1e-6, 1e6) coefficient priors, which under the new classes span λ² rather than λ⁴ — plus power: {type: Constant, value: 1.0} so the convention switch is never sampled by a search.
• docs/api/pixelization.rst gains AdaptPower / AdaptSplitPower in the ag.reg autosummary.
• test_autogalaxy/test_regularization_power.py proves the ag.reg re-export chain, that af.Model exposes exactly inner_coefficient / outer_coefficient / signal_scale (not power), and that the identifier differs from the legacy class.

CI note: green here already. The PyAutoHeart reusable workflow clones each dependency library at the matching branch if it exists, and PyAutoArray#512 uses the same branch name, so this PR's CI tested against it. Library-first merge order still applies for main's sake: merge PyAutoLabs/PyAutoArray#512 first, otherwise main here would reference ag.reg.AdaptPower before the symbol exists.

API Changes

None to autogalaxy source — config, docs and test additions only. The new public symbols are added upstream in PyAutoLabs/PyAutoArray#512 and reach users here as ag.reg.AdaptPower, ag.reg.AdaptSplitPower, ag.reg.AdaptSplitZerothPower, ag.reg.MaternAdaptPowerKernel.
See full details below.

Test Plan

• pytest test_autogalaxy/ — 1152 passed (with PyAutoArray#512 on PYTHONPATH)
• af.Model(ag.reg.AdaptSplitPower) composes; power resolves to the Constant value 1.0 and is absent from the prior tuples
• af.Model(ag.reg.AdaptSplit).identifier != af.Model(ag.reg.AdaptSplitPower).identifier
• CI green on all four legs (unittest 3.12 / 3.13 / nojax, docs-build), tested against the PyAutoArray branch

Full API Changes (for automation & release notes)

Added

• Prior configs for AdaptPower, AdaptSplitPower, AdaptSplitZerothPower and MaternAdaptPowerKernel — the coefficient priors are unchanged copies of the legacy schemes' (LogUniform(1e-6, 1e6)), and power is a Constant prior fixed at 1.0.
• docs/api/pixelization.rst autosummary entries for AdaptPower and AdaptSplitPower.

Migration

• Before: ag.reg.AdaptSplit(inner_coefficient=c, outer_coefficient=c)
• After: ag.reg.AdaptSplitPower(inner_coefficient=c**2, outer_coefficient=c**2)
• The legacy schemes and their prior configs are untouched, so no migration is required — this is guidance for new work.

Depends on PyAutoLabs/PyAutoArray#512. Refs PyAutoLabs/PyAutoArray#511.

Generated by the PyAutoLabs agent workflow.