feat: preserve tag/status/description when generating constants

[acul71]

Summary

Closes #38.

• Update tools/update-table.py to write tag, status, and description into each CODECS entry
• Regenerate multicodec/constants.py from upstream table.csv
• Keep NAME_TABLE / CODE_TABLE prefix lookups working (typed + cast)
• Ignore E501 on generated constants.py in ruff.toml
• Add tests/test_constants_metadata.py

Does not close #39/#47 (no Code.status / Code.description API yet).

Demo

BEFORE (master):
    "sha2-256": {
        "prefix": 0x12,
    },

AFTER:
{'prefix': 18, 'tag': 'multihash', 'status': 'permanent', 'description': ''}
NAME_TABLE['sha2-256'] == 18
total codecs: 651

Test plan

• make lint / typecheck / test / docs-ci locally
• Newsfragment 38.internal.rst present
• CI green on this PR
• Review asked from @sumanjeet0012 (comment; formal request requires collaborator status)

Made with Cursor

[acul71]

@sumanjeet0012 Could you please review this PR when you have a chance? Thanks!