Follow-up on the cherry-picked #36896 commits, wiring 1Password into
the new registry as the reference *mapped* source:
- OnePasswordSource adapter (shape=mapped, scheme=op): fetch-only —
precedence, override semantics, conflict warnings, and env writes
move to the orchestrator; apply_onepassword_secrets kept as legacy
shim like Bitwarden's.
- Registered in _ensure_builtin_sources; mapped op:// bindings now
outrank bulk Bitwarden project dumps on contested vars.
- _cache.py FetchResult/is_valid_env_name re-exported from base so
there is exactly one canonical definition; bitwarden.py re-adapted
onto the contributor's DiskCache substrate.
- ErrorKind classification for op failures (auth/binary/empty/network).
- Registry + conformance coverage for OnePasswordSource, incl. the
headline multi-source test: both vaults claim the same var, mapped
1Password wins, conflict surfaced, provenance correct.
- env_loader tests migrated off the legacy apply_* mocks onto the
fetch layer; AUTHOR_MAP entry for @hwrdprkns.