refactor: categorize code_table constants by CSV tag

[acul71]

Summary

Closes #43.

Depends on #56 (issue #38) — this PR is stacked on issue-38.

• Replace name-pattern categorization in tools/gen_code_table.py with CSV tag from enriched CODECS
• Regenerate multicodec/code_table.py (sections now include softhash, nonce, vlad, etc.)
• Add unit tests for categorize()

Demo

=== BEFORE (pattern-based excerpt from previous code_table on master) ===
18:# Multihash
577:# Other
Generated /home/luca/Informatica/Learning/PNL_Launchpad_Curriculum/Libp2p/py-multicodec/.worktrees/issue-43/multicodec/code_table.py
Total constants: 651
=== AFTER (tag-based sections) ===
1:# Code generated from constants.py; DO NOT EDIT MANUALLY.
3:# To regenerate, run: python tools/gen_code_table.py
5:# These constants provide type-safe Code values for all known multicodecs,
6:# allowing usage like:
7:#     from multicodec import SHA2_256
8:#     code = SHA2_256  # Code object for sha2-256
10:# Instead of:
11:#     from multicodec import Code
12:#     code = Code(0x12)
18:# multihash
379:# multiaddr
426:# ipld
473:# serialization
488:# multiformat
499:# key
590:# namespace
614:# cid
619:# encryption
622:# filecoin
626:# hash
639:# holochain
647:# libp2p
652:# multikey
655:# multisig
675:# nonce
678:# shelter
685:# softhash
688:# transport
694:# varsig
707:# vlad
710:# zeroxcert
676:NONCE: Code = Code(0x123b)  # nonce
686:ISCC: Code = Code(0xcc01)  # iscc
708:VLAD: Code = Code(0x1207)  # vlad

Test plan

• make lint / typecheck / test / docs-ci locally
• Newsfragment 43.internal.rst present
• CI green on this PR
• Review asked from @sumanjeet0012
• Merge only after feat: preserve tag/status/description when generating constants #56 lands (or retarget base to master)

Made with Cursor

[acul71]

@sumanjeet0012 Could you please review this PR when you have a chance? (Depends on #56.) Thanks!