- kb-config::apply_env now covers every leaf key in `Config` via an
explicit grep-friendly match block (one arm per leaf), keyed
`KB_<SECTION>_<KEY>`. Booleans flow through a shared `parse_bool` helper.
Numeric leaves silently keep their prior value on parse failure so a
malformed env entry can't crash startup.
- New tests: env_unknown_key_is_ignored,
env_overrides_chunking_target_tokens,
env_overrides_models_llm_endpoint_and_temperature,
env_overrides_indexing_watch_filesystem_bool.
- kb-app::logging::init now returns `Result<WorkerGuard>` instead of
`Result<Option<WorkerGuard>>` — the inner `Option` was always `Some` so
the wrapper was dead. kb-cli/main.rs collapses the call from
`.ok().flatten()` to `.ok()`, preserving fail-soft semantics on logging
init.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>