Rust composed exit and intermission state machine

RE-843. Reproduce with python3 scripts/analyze_rust_intermission_flow.py; focused validation: cargo xtask test-group rust-intermission-flow. Machine report.

Rust composes recovered tie, readiness, begin and exit-log policies with prior exit timers/limits across150 continuous source fixtures. Atomic staged updates preserve shared pending/client state; reset and lower-level world/I/O effects remain explicit intentions. Source branch labels are independently classified by the tested composition oracle; captured requests and actual final source state supply effect parity.

Original executable/native runtime and complete Linux/macOS Rust/Bevy/Solari acceptance remain unverified.