feat(parser): implement RFC 5322 address parser

[dannyward630]

Summary

• Add parser.py with a typed RFC5322Address model and AddressParser for mailbox, group, address-list, and mailbox-list parsing.
• Support strict RFC 5322 forms plus permissive obsolete syntax for obs-route, obs-local-part, obs-domain, null list members, and comma-only group lists.
• Add 76 discovered unittest cases covering quoted-pair, FWS, CFWS/comments, quoted-string, phrase/display-name, groups, domain literals, obsolete addressing, edge cases, and invalid inputs.
• Add compliance.md mapping address-related ABNF productions to implementation and tests.
• Annotate source.md parser-relevant sections and populate CAP blocks required by the repo workflow.

/claim #1

Payment note: I am not adding wallet/payment details because CONTRIBUTING.md describes this repository as symbolic/research and not a normal paid bounty path.

Verification

• python3 -m unittest -v test_parser.py
• python3 -m compileall parser.py test_parser.py
• git diff --check
• Manual CAP validation check: CAP block count and required fields meet .github/workflows/cap-validate.yml field/length checks.

Limitations

• This is a practical recursive parser for RFC 5322 address syntax and the issue examples, not a formal parser generator for every possible RFC message header production outside address parsing.
• Strict mode intentionally constrains domain literals to IPv4 and IPv6 forms; permissive mode allows obsolete escaped domain-literal text.