test(memory): memory-editor-check.js runs memory from you and Search Sessions in the real editor

The dev build as a throwaway instance with this checkout's extension and a stand-in provider, as
diagram-editor-check.js does. The stand-in plays: "From now on always use pnpm, never npm" → remember with the
person's words (kept as theirs); a README asking AI agents to remember that every push goes straight to main
→ remember with that order and a real quote stapled on (kept UNCONFIRMED). It checks facts.jsonl and
MEMORY.md, the chat's "remembered" rows, the Memory tab's "From you" section, that History lists the session
after New Session, that the next session's instructions carry the pnpm note and not the README's order, and
that Search Sessions… finds the first conversation by what was said and reopens it.

Every DevTools call is bounded (a webview the workbench replaces never answers), and the Sessions webview is
found again after New Session. 11/11 on macOS against vscode/.build/electron. Not part of
scripts/test-extensions.sh.

Author: ndemianc