Task: Integrate remember password into main

Identity

Integrate verified remember-password source commit 990639f into local main.
Reconcile the source task's accepted authentication promotion candidates into canonical current-state, architecture, ADR, and domain documents.
Preserve the pre-existing untracked packaging task record without modifying or committing it.

Keep remembered credentials separate from the existing seven-day Works Square session.
Keep password persistence Main-owned and OS-encrypted in packaged builds; do not persist passwords in Renderer or Works Square.
Preserve logout/SMS retention and successful unchecked-password-login clearing semantics.
Merge only to local main; do not push.

Source feature commit 990639f was created from the completed isolated feature worktree.
Merged the source branch into local main as merge commit 2b9f84e without conflicts; README auto-merged with the already integrated Session-model documentation.
Promoted the accepted remembered-password boundary into current-state.md, system-overview.md, ADR-004, and business-rules.md.
Preserved .project-docs/30-worklog/tasks/20260819-package-learning-off-115-9c4d.md untouched and untracked.

Source verification: 79 focused tests, typecheck, scoped ESLint, and Vite Renderer/Main/Preload/utility build passed.
Integrated local main: 4 focused test files / 79 tests passed.
Integrated local main: pnpm run typecheck passed.
Integrated local main: scoped ESLint passed with zero errors.
Integrated local main: Renderer/Main/Preload/utility pnpm run build:vite passed with existing dynamic-import and large-chunk advisory warnings only.
git diff --check passed with line-ending conversion notices only.
Required project-docs structure check passed.
Task-aware documentation drift is blocked by two read-only foreign task records: the pre-existing, explicitly preserved untracked .project-docs/30-worklog/tasks/20260819-package-learning-off-115-9c4d.md, and the source task record .project-docs/30-worklog/tasks/20260820-makelore-remember-password-b63e1c.md introduced unchanged by merge commit 2b9f84e. The integration did not modify either record. The checker also lists the expected merged source files as non-document changes.

Run packaged Windows and signed macOS smoke for OS-protected save, restart prefill, successful unchecked-login clear, and no development Keychain prompt.
Resolve the repository's integration drift-check handling for unchanged source task records and decide the separately owned untracked packaging record before this integration ownership can be completed and released cleanly.