Remove "PR #14984 / #27371 / #1969" references and "the original key /
legacy / backwards-compatible / Port #N" narration from the honcho
plugin README, tests, and one stale code comment. These artefacts age
poorly: they describe how a change happened rather than what the code
does today, and they tax readers who weren't around for the original
work.
Also drop a dangling reference to scratch/memory-plugin-ux-specs.md in
__init__.py — the file isn't in the repo or git history.
No behaviour change.
939499beed