[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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---

Summary

#1103 round 2: the files phase 1 left unread, plus the phase-1 reviewers' follow-ups.

Reads the MH, HOPOPT, IPv6-Opts, IPv6-Route and ESP prose phase 1 left
unread, with their schemas, data models and pages.

• Data models: versionchanged on the 31 classes that gained a required
  field since 1.4.1.post2, each citing the issue the field came from.
• HOPOPT/IPv6-Opts, IPv6-Route and MH class directives gain the missing
  fix(ipv6): reserved bits not named in a BitField are written back as zero (Frag, RPL routing, MPL, IP_DFF, Quick-Start) #1235 reserved-bit, IP_DFF length and fix(corekit): non-zero padding octets are zeroed on rebuild #1223 padding rows; MH's also
  cites fix(mh): reserved fields, BU/BA flag bits and PadN contents are written back as zero #1329 for its reserved fields and flag bits.
• MH dispatch note: Schema subclasses each have their own ABC cache (Schema subclasses share one ABCMeta cache on Python <=3.10, so isinstance/issubclass return whichever answer was asked first #439).
• Drop four stale TODOs: every MH type, option and CGA extension has a
  handler. MH and ESP modules are not "MH/ESP only"; esp.rst drops an
  unchecked "unlike every other protocol"; MH's table names mh.reserved.
• Field comments: lengths are octets, an option length includes its
  header, Type 2 holds one address; fix typos (router alter, cation,
  Retune, ANSI.1, LAA), two mislabelled data models, a from_dict link.

AST guard: 16 .py files identical; tests/project and related tests pass.

Refs #1103

[JarryShaw]

Verdict: GOOD TO GO at ff98e9505. Sonnet review and re-check (author: Opus). The first review blocked: four mh.py directives cited #1324 for fields that came with #1329. The fix round corrected the citations against #1345. The AST guard is identical against the base, tests/project passes, and every added directive says 1.5.0.