Add write support

[DavidMStraub]

No description provided.

[Copilot]

Pull request overview

Adds GEDCOM 7 serialization (“write support”) to complement the existing parser, including a public API (dump/dumps) and comprehensive round-trip/validation tests.

Changes:

• Introduces gedcom7.serializer with dumps()/dump() and serialization validations (tags, xrefs/pointers, CONT splitting, banned characters, BOM, line terminators).
• Updates core types/exceptions and package exports to support reliable equality (parent excluded from comparisons) and a new GedcomSerializeError.
• Adds serializer-focused tests and updates README to document parsing + writing usage.

Reviewed changes

Copilot reviewed 6 out of 6 changed files in this pull request and generated 2 comments.

Show a summary per file

File	Description
test/test_serializer.py	New test suite covering round-trips, encoding details, and serialization error cases
README.md	Updates project description and adds serializer usage + dev command summary
gedcom7/types.py	Excludes parent from dataclass comparison/repr to prevent recursive equality/representation
gedcom7/serializer.py	New serializer implementation providing dumps/dump with spec-aligned formatting and validations
gedcom7/exceptions.py	Adds GedcomSerializeError exception type
gedcom7/init.py	Exports serializer API (dump, dumps) and GedcomSerializeError

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[Copilot]

Pull request overview

Copilot reviewed 7 out of 7 changed files in this pull request and generated no new comments.

Suppressed comments (3)

gedcom7/serializer.py:24

• The BOM constant is defined as an invisible literal character, which is easy to miss/corrupt in editors and diffs. Using an explicit "\ufeff" escape makes this clearer and less error-prone.

_BOM = ""

test/test_serializer.py:81

• This test asserts on an invisible BOM literal character. Using the explicit "\ufeff" escape makes the intent clearer and avoids issues if the file encoding/renderer hides or mangles the character.

    """The specification says a data stream should begin with U+FEFF."""
    out = gedcom7.dumps(gedcom7.loads(HEAD + TRLR))
    assert out.startswith("")
    assert gedcom7.dumps(gedcom7.loads(HEAD + TRLR), byte_order_mark=False) == (
        HEAD + TRLR

README.md:40

• The Development command omits the formatting check that CI enforces (workflow runs ruff format --check .), so following the README can still fail CI due to formatting.

pytest && mypy && ruff check .