feat(phase32): L-2.1 Stage-1 UsingResolver JoinIR integration + cleanup
Phase 32 L-2.1 complete implementation:
1. Stage-1 UsingResolver main line JoinIR connection
- CFG-based LoopForm construction for resolve_for_source/5
- LoopToJoinLowerer integration with handwritten fallback
- JSON snapshot tests 6/6 PASS
2. JoinIR/VM Bridge improvements
- Simplified join_ir_vm_bridge.rs dispatch logic
- Enhanced json.rs serialization
- PHI core boxes cleanup (local_scope_inspector, loop_exit_liveness, loop_var_classifier)
3. Stage-1 CLI enhancements
- Extended args.rs, groups.rs, mod.rs for new options
- Improved stage1_bridge module (args, env, mod)
- Updated stage1_cli.hako
4. MIR builder cleanup
- Simplified if_form.rs control flow
- Removed dead code from loop_builder.rs
- Enhanced phi_merge.rs
5. Runner module updates
- json_v0_bridge/lowering.rs improvements
- dispatch.rs, selfhost.rs, modes/vm.rs cleanup
6. Documentation updates
- CURRENT_TASK.md, AGENTS.md
- Various docs/ updates
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Co-Authored-By: Claude <noreply@anthropic.com>
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