fix(corekit): give unnamed ListField, PayloadField and SchemaField a default name (#1491)

[JarryShaw]

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• Added a changelog entry under docs/source/changelog/ and regenerated CHANGELOG.md, if the change is user-visible — N/A — centralised in docs(changelog): shared 1.5.0 changelog — long-lived, merges last (#610, #616, #617, #618, #620) #657

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ListField.__init__, PayloadField.__init__ and SchemaField.__init__ set no _name, so .name on an unnamed instance (and on OptionField/ChunkListField) raised AttributeError. Each now uses the hasattr default from FieldBase.__init__ and Field.__init__ (field.py:348, field.py:614): <list>, <option>, <chunklist>, <payload>, <schema>. A name set by __set_name__ still wins. SwitchField and ForwardMatchField delegate to the wrapped field and are unchanged.

New tests/corekit/test_fields_collections_default_name_1491_unit.py. Fail-before: the ListField cases failed (4 failed / 2 passed) against origin/main's collections.py, and the PayloadField/SchemaField cases failed (2 failed / 4 passed) against origin/main's misc.py. With the fix: 6 passed, 2 subtests passed.

Ran (not make test): that file, tests/corekit (474 passed), tests/project (419 passed, 1 skipped), tests/test_docstring_contract.py (7 passed). Lint not run.

Closes #1491

[JarryShaw]

Verdict: GOOD TO GO at 7ea03dde4. Cross-reviewed on Sonnet; the author ran on Opus.

• The fix works. I measured it myself: on origin/main sources the new tests give 6 failed, 2 passed; at head, 6 passed. Unnamed ListField, PayloadField and SchemaField now get <list>, <payload> and <schema>, the field.py:348-349 idiom.
• Schema names still win. All 23 ListField/OptionField/PayloadField/SchemaField attributes in the SCTP, IPv4 and TCP schemas keep their attribute names, including on copies, because __set_name__ runs after __init__.
• Subclasses: OptionField, ChunkListField, OptionAreaField and SchemaField give <option>, <chunklist>, <optionarea> and <schema>. Every subclass name ends in Field, so none is garbled.
• Regression checks: the per-capture to_dict() hashes are identical across all 23 captures. The round-trip files and tests/corekit, tests/project and the docstring contract pass: 900 passed, 1 skipped.

Non-blocking: the leftover #self._name = '<list>' comment in collections.py matches the one field.py:613 keeps.

[github-actions]

Coverage: 89.65% (unit tier, Python 3.14, 7ea03dde4, Unit Tests run success)

Package	Statements	Missed	Branches	Partial	Cover
pcapkit (top level)	104	4	20	4	93.55%
pcapkit/const	18795	958	2356	871	90.99%
pcapkit/corekit	2113	66	678	33	96.17%
pcapkit/dumpkit	242	2	88	2	98.79%
pcapkit/foundation	2648	98	930	48	94.80%
pcapkit/interface	112	7	40	5	92.11%
pcapkit/protocols	17086	238	4628	190	97.98%
pcapkit/toolkit	539	74	168	3	84.58%
pcapkit/utilities	431	4	124	4	98.56%
pcapkit/vendor	4409	2342	1006	157	43.25%

Per-file detail: the coverage-html artifact of this run.