phase(9.78h): stabilize MIR/VM pipeline

- Add MIR26 doc≡code sync test (tests/mir_instruction_set_sync.rs)
- Quiet snapshots; filter plugin/net logs; golden all green
- Delegate VM phi selection to LoopExecutor (borrow-safe)
- ResultBox migration: remove legacy box_trait::ResultBox paths
- VM BoxRef arithmetic fallbacks via toString().parse::<i64>()
- Bridge BoxCall(InstanceBox) to Class.method/arity in VM
- Fix Effects purity (READ -> readonly, not pure)
- Mark Catch as CONTROL to prevent DCE; Try/Catch test green
- Add env-gated debug logs (effects, verifier, mir-printer, trycatch, ref, bin)
- Update CURRENT_TASK with progress and next steps

src/debug/mod.rs

@@ -0,0 +1,2 @@
+pub mod log;
+