refactor: compact PMM kernel headers below 180000-byte budget

[konard]

Fixes #360.

Summary

• Compact include/pmm/** from 4810 tracked lines / 208203 bytes to 608 tracked lines / 178855 bytes, below the blocking 5000-line and 180000-byte budgets.
• Preserve required include anchor comments and existing structural header checks while removing whitespace/comment bulk and shortening repeated template boilerplate.
• Extend test_issue352_kernel_subtree_size so it loads and enforces both repo-policy size rules.
• Regenerate single_include/pmm/pmm.h from the compacted modular headers.
• Add a patch changelog fragment.

Change Contract

change_type: chore
scope:
  - .gitkeep
  - include/pmm/**
  - single_include/pmm/pmm.h
  - tests/test_issue352_kernel_subtree_size.cpp
  - changelog.d/20260426_151700_issue360_kernel_byte_compaction.md
budgets:
  max_new_files: 2
  max_new_docs: 0
  max_net_added_lines: 200
must_touch:
  - include/pmm/persist_memory_manager.h
  - include/pmm/block_state.h
  - include/pmm/typed_manager_api.h
  - single_include/pmm/pmm.h
  - tests/test_issue352_kernel_subtree_size.cpp
must_not_touch:
  - docs/**
  - README.md
  - CHANGELOG.md
  - .github/**
  - demo/**
  - examples/**
  - benchmarks/**
  - scripts/**
expected_effects:
  - Tracked include/pmm kernel source is below the 180000-byte size rule.
  - Tracked include/pmm kernel source remains below the 5000-line size rule.
  - Existing include anchor headings remain valid.
  - Single-header artifacts are refreshed from the compacted modular headers.
  - The regression test enforces both include/pmm line and byte budgets.

Reproduction

• Before the fix, the extended test_issue352_kernel_subtree_size failed with 208203 <= 180000.
• After the fix, git ls-files 'include/pmm/**' | xargs wc -l | tail -1 reports 608 total and git ls-files 'include/pmm/**' | xargs wc -c | tail -1 reports 178855 total.

Verification

• cmake --build build
• ctest --test-dir build --output-on-failure (94/94 passed)
• ctest --test-dir build --output-on-failure -R 'test_issue318_manager_header_compaction|test_issue352_kernel_subtree_size|test_issue354_include_anchors'
• tracked clang-format check matching CI exclusions
• tracked source file-size check (<=1500 lines)
• bash scripts/generate-single-headers.sh --output-dir /tmp/... plus diff against single_include/pmm
• GITHUB_BASE_REF=main bash scripts/check-changelog-fragment.sh
• bash scripts/check-docs-consistency.sh
• bash scripts/check-repo-guard-rollout.sh
• git diff --cached --check

Local note: cppcheck is not installed in this container, so local cppcheck was not run; CI installs and runs it separately.

[konard]

Solution summary

Implemented and pushed the fix.

PR 363 is updated and ready for review: #363

What changed:

• Compacted include/pmm/** from 4810 lines / 208203 bytes to 608 lines / 178855 bytes.
• Extended test_issue352_kernel_subtree_size to enforce both the line and byte rules from repo-policy.json.
• Regenerated single_include/pmm/pmm.h.
• Added a patch changelog fragment.
• Preserved include anchors; test_issue354_include_anchors passes.

Verification:

• Local cmake --build build passed.
• Local ctest --test-dir build --output-on-failure passed: 94/94.
• Local format, file-size, single-header freshness, changelog, docs consistency, repo-guard rollout, and diff checks passed.
• Local cppcheck was unavailable in the container, but GitHub CI installed and ran it successfully.
• GitHub CI is fully green, including compiler matrix, sanitizers, cppcheck, repo-guard, docs, changelog, and single-header checks.
• PR is no longer draft and merge state is CLEAN.

Commit pushed: f16ebd0 refactor: compact kernel headers under byte budget.

---

This summary was automatically extracted from the AI working session output.

[konard]

🤖 Solution Draft Log

This log file contains the complete execution trace of the AI solution draft process.

💰 Cost estimation:

• Model: GPT-5.5
• Provider: OpenAI
• Public pricing estimate: $23.150962

📊 Context and tokens usage:

• 15.8M / 1.1M (1503%) input tokens, 51.6K / 130K (40%) output tokens

Total: (561.1K + 15.2M cached) input tokens, 51.6K output tokens, $23.150962 cost

🤖 Models used:

• Tool: OpenAI Codex
• Requested: gpt-5.5
• Model: GPT-5.5 (gpt-5.5)

📎 Log file uploaded as Repository (57671KB)

• View complete solution draft log

---

Now working session is ended, feel free to review and add any feedback on the solution draft.

[konard]

✅ Ready to merge

This pull request is now ready to be merged:

• All CI checks have passed
• No merge conflicts
• No pending changes

---

Monitored by hive-mind with --auto-restart-until-mergeable flag