Mark lost mob sessions broken

[lukacf]

Summary

• record a missing current mob bridge session into MobMachine-owned member_restore_failures during deep member_status inspection
• fail fast with MemberRestoreFailed when work dispatch targets a missing bridge session, instead of surfacing generic session/injector plumbing or leaving the member looking active
• add regression coverage for member_status diagnostics, post-probe list/work behavior, and direct submit_work without a prior status probe
• expand BuildBuddy edge detection so meerkat-mob/* changes run SDK, minimal, feature, WASM, and audit/security lanes

Validation

• ./scripts/repo-cargo fmt --check
• ./scripts/repo-cargo test -p meerkat-mob missing_bridge_session -- --nocapture
• ./scripts/repo-cargo test -p meerkat-mob member_status -- --nocapture
• ./scripts/repo-cargo test -p meerkat-mob broken_member -- --nocapture
• ./scripts/repo-cargo test -p meerkat-mob
• printf 'meerkat-mob/src/runtime/actor.rs\nmeerkat-mob/src/runtime/tests.rs\n' | scripts/buildbuddy-edge-changes --paths-from-stdin
• make buildbuddy-doctor
• pre-push hooks: secrets, whitespace, fmt, changed-crate clippy, machine codegen+verify, generated-header audit, bridge invariant, Bazel freshness, deterministic workspace gate