fix: stop writing the literal comment [''] on every header_dict FITS card

[Jammy2211]

Summary

hdu_list_for_output_from passed a list, [""], as the FITS card comment. astropy does not reject it — it str()s it — so every card written from a header_dict landed on disk reading:

PIXSCAY =                  0.1 / ['']
PIXSCAX =                  0.1 / ['']
ORIGINY =                  0.0 / ['']
ORIGINX =                  0.0 / ['']

Every Imaging dataset the stack writes carries this on four cards, and it renders for anyone opening a PyAuto FITS in DS9, astropy, or any external tool. Cosmetic, but it is output we hand to other people, and it reads as a serialization bug.

The intent was clearly an empty comment. "" gives that; the list gave the rendered repr of a list. Verified on disk — the card becomes a plain PIXSCAY = 0.1, no comment, no trailing slash, byte-size unchanged.

Found while implementing the regime stamp (#153/#154) and deliberately left out of that change so a cosmetic fix did not ride along with a behavioural one.

API Changes

None — internal changes only.

Nothing reads FITS comments anywhere in the stack — every header consumer indexes values by key name, verified across PyAutoArray, PyAutoGalaxy, PyAutoLens and the workspaces during #153. Values, keys, and card order are untouched.

A decision taken explicitly

The prompt raised adding real per-key comments, since PIXSCAY/ORIGINY are not self-describing to an outside reader and the slot is already there. Not doing it, deliberately.

autonerves receives an opaque header_dict and does not know the key vocabulary — PIXSCAY/PIXSCAX/ORIGINY/ORIGINX are autoarray's Mask2DKeys. Hardcoding their meanings in the base serialization layer would couple it to a downstream key set, which is the wrong direction for the dependency. If descriptive comments are wanted, the caller should be able to supply them — that is a separate API change to header_dict's shape, not a rider on this.

Test Plan

• python -m pytest test_autonerves/ — 166 passed
• Green and byte-identical with PYAUTO_SMALL_DATASETS=1 exported and unset
• On-disk card verified: A = 1 with no comment; the SMALLDAT stamp keeps its real comment, so this removes junk rather than all comments
• Regression test pins the comment empty and asserts no [ in the rendered card
• Fixture rewrite verified byte-stable across repeated runs (identical md5)

Fixture refresh

test_autonerves/files/array_out.fits is a test write target — the suite rewrites it every run — so its committed bytes change with the comment. Refreshed here.

The autouse conftest fixture added in #154 pins PYAUTO_SMALL_DATASETS for the suite, so this rewrite is deterministic regardless of the shell it runs in; confirmed by getting identical bytes with the variable exported and unset.

Generated by the PyAutoLabs agent workflow.

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