Add recovery gate: require direct validation of primary target before new executable artifacts are used

[mmprotest]

Motivation

• Prevent runaway "sideways" recovery where a hard failure on the primary execution target leads the runner to create new executable/verifier artifacts that also fail instead of restoring the broken target.
• Ensure the primary_execution_target and minimal-recovery state are actually reflected in the live mission snapshot used by execution/control, fixing the observed plumbing gap.

Description

• Mirror recovery fields into mission snapshots by adding recovery_mode, primary_execution_target, and primary_target_minimally_valid to MissionState and wiring them into Runner._update_mission_state and state_runtime sync APIs.
• Seed and sync the live primary target during verification via _seed_primary_execution_target and a new _sync_recovery_state_to_mission helper in villani_code/state_runtime.py.
• On hard failure capture a snapshot of repository file paths and reset created-artifact tracking, and set _primary_target_minimally_valid = False so recovery is explicit.
• Track newly created files during recovery in the tooling lifecycle by recording write-created files in villani_code/state_tooling.py.
• Add a narrow recovery gate in small_model_tool_guard so, while runner._recovery_mode is active, any proposed validation/launch target that is confidently new (created during recovery or absent at failure snapshot) is blocked with structured feedback instead of permitting a switch to a newly introduced executable.
• Clear recovery only after a direct minimal validation of the same primary_execution_target succeeds and mark _primary_target_minimally_valid = True when that validation passes.
• Files changed: villani_code/mission_state.py, villani_code/state.py, villani_code/state_runtime.py, villani_code/state_tooling.py, and tests tests/test_state_runtime.py, tests/test_state_tooling_mutation_policy.py, tests/test_mission_state_runtime.py.

Testing

• Ran pytest -q tests/test_state_runtime.py tests/test_state_tooling_mutation_policy.py tests/test_mission_state_runtime.py; the run completed successfully with all tests passing (74 passed).
• Added/updated unit tests that assert: first meaningful validation seeds primary_execution_target, hard failure sets recovery_mode and clears minimal-valid flag, recovery blocks creation/use of new validation artifacts, helper edits and bounded patches remain allowed, and mission snapshot reflects the live recovery/primary-target state.

---

Codex Task