feat(phi): Phase 25.1 - BTreeMap移行 (21ファイル、80%決定性達成)

## 修正内容

### Core MIR/PHI (5ファイル)
- builder.rs: variable_map, value_types, value_origin_newbox
- context.rs: 3つのマップ
- loop_builder.rs: 3箇所
- loop_snapshot_manager.rs: snapshot マップ
- loop_snapshot_merge.rs: 2箇所

### MIR関連 (4ファイル)
- function.rs: FunctionMetadata.value_types
- resolver.rs: CalleeResolverBox
- guard.rs: CalleeGuardBox
- loop_common.rs: apply_increment_before_continue

### JSON Bridge (5ファイル)
- json_v0_bridge/lowering.rs
- json_v0_bridge/lowering/expr.rs
- json_v0_bridge/lowering/if_else.rs
- json_v0_bridge/lowering/merge.rs
- json_v0_bridge/lowering/try_catch.rs
- json_v0_bridge/mod.rs

### Printer & Providers (4ファイル)
- printer.rs, printer_helpers.rs
- host_providers/mir_builder.rs
- backend/mir_interpreter/handlers/extern_provider.rs

### Tests (3ファイル)
- phi_core/conservative.rs
- tests/json_program_loop.rs
- tests/mir_stage1_using_resolver_verify.rs (2テスト有効化)

## テスト結果
- mir_stage1_using_resolver_resolve_with_modules_map_verifies: 80%成功率
- 完全な決定性は未達成 (HashMap 86箇所、HashSet 63箇所が残存)

🐱 Generated with Claude Code

tests/json_program_loop.rs

@@ -1,11 +1,11 @@
 use serde_json::json;
-use std::collections::HashMap;
+use std::collections::BTreeMap;
 
 fn verify_program(label: &str, program: serde_json::Value) {
     let src = serde_json::to_string(&program).expect("serialize program");
     let module = nyash_rust::runner::json_v0_bridge::parse_json_v0_to_module_with_imports(
         &src,
-        HashMap::new(),
+        BTreeMap::new(),
     )
     .unwrap_or_else(|e| panic!("{}: failed to parse Program(JSON): {}", label, e));