hakorune/src/mir/join_ir_vm_bridge_dispatch

JoinIR VM Bridge Dispatch

Purpose:

• Centralize JoinIR→VM routing away from the VM runner.
• Table-driven mapping of MIR function names to JoinIR lowering/exec behavior.
• Keep Exec vs LowerOnly paths explicit and opt-in via env flags or defaults.

Layout:

• mod.rs: public entry (try_run_joinir_vm_bridge) + shared routing glue
• env_flags.rs: env flag evaluation (NYASH_JOINIR_EXPERIMENT, NYASH_JOINIR_VM_BRIDGE)
• targets.rs: descriptor table (JOINIR_TARGETS, JoinIrBridgeKind, JoinIrTargetDesc)
• exec_routes.rs: Exec-capable routes (skip_ws, trim)
• lower_only_routes.rs: LowerOnly routes (Stage1/StageB) for structural verification only