Beads: integrate remaining member-import branch with safe append

Integrates codex/mingiyan-beads-access into current main while retaining current client profiles and onboarding. The importer can add new members without replacing existing access. Fixes stale temporary-file detection before account creation, private backup creation, failed publication cleanup, and unsafe optimized/abbreviated invocation; adds 15 isolated regression cases and operator guidance. Validation: 314 Python CI tests, 14 Node tests, 21 documentation tests and 1683 documentation checks passed; independent security review passed. Real accounts and server access were not changed. Late provisioning failures still require administrator inspection. The 17 legacy R1/docs branches are excluded because their input, railway and delivery contracts conflict with APP-2026-09-19. Related tracking: trasser-org03; tracker unavailable because SSH closes before context verification, so no tracker update was made.