docs(qa): platform-core ledger edits from the 18.2.0 sweep's run records

Eleven platform-core items revised against main, each with its revision
bumped and a history row citing the run record its line came from: QA
run #25812 (boot-health, nav-surfaces-render, builtin-apps-nav-render,
seed-integrity, v18-boot-refusals) and QA run #25815
(activation-ledger-registration-home, activation-ledger-row-contract,
lifecycle-retention-sweep, metadata-registry-serving,
serve-composition-v18, nav-surfaces-render, v18-boot-refusals).

The file's two remaining prescriptions of the retired objectui pin
(`pnpm objectui:build` in boot-health, the .objectui-sha revision in
keyboard-shortcut-surface) now name `pnpm console:build` and the ui/
path.

Claude-Session: https://claude.ai/code/session_01VoWrGZipReMqGbFdsvCLsX
Co-authored-by: Claude <noreply@anthropic.com>

Author: claude