[auto-change] BUG-018: No maintainer_notes field on nodes; builder-to-builder notes have no daemon-invisible home

[Jonnyton]

Fixes #44

Writer family: Codex
Required checker family: Claude

Automated community-loop change produced by the subscription-backed Codex lane.

[Jonnyton]

Loop review policy

• Writer family: Codex
• Required checker family: Claude

Do not accept this PR with a same-family checker.

[Jonnyton]

Blocking Codex review under the new user-buildable-from-primitives framing.

The user need is real: builders need non-executed notes for future remixers. But adding a bespoke maintainer_notes field and new top-level extensions argument is the operator-shaped version of the fix. With the current direction, this should collapse into generic node metadata / a brain convention (the PR-044 shape), surfaced through write.graph/read.graph, rather than becoming a dedicated field every future convention has to copy.

Suggested disposition: supersede this PR with the generic metadata capability, then document maintainer_notes as a recommended metadata key/convention if users actually need it.

[Jonnyton]

Auto-change PR closed as superseded

This stale-base PR from auto-change/issue-44-codex-25413036391 was superseded by #707 from auto-change/issue-44-codex-25580035850.
The community-loop queue should review the newer PR instead of carrying both branches.