personal memory agent

feat(setup): install the local brain in the background on capable hosts; add --skip-brain master

`journal setup` now appends a `brain` step that selects the local provider lane (providers.generate/cogitate = "local") and triggers the existing background bootstrap via `sol call thinking local bootstrap`, returning without waiting for the multi-GB download. The step never fails setup. It defers — lane set, no brain, rc 0 — when --skip-brain is passed, when --skip-models implies it, when --skip-service means convey is unreachable, or when build_check_report() returns a blocked verdict. An owner-chosen non-local provider is preserved untouched. Deferral is honest, not silent: readiness_for_provider("local") already reports local_model_missing, which Convey renders as "local model setup is not finished" with a route to Settings. processing.mode is deliberately untouched — "deferred" means "drain during the nightly window", a promise a brainless host cannot keep. TOTAL_STEPS is now derived from _STEPS, and print_plan enumerates _STEPS through a _PLAN_BODY map that raises on an unmapped step, so the step count has one source of truth.