refactor(phase62): Delete phi_input_collector.rs (-384 lines)

Phase 62前倒し: PhiInputCollectorの物理削除

Changes:
- Delete src/mir/phi_core/phi_input_collector.rs (-384 lines)
- Inline PhiInputCollector logic in json_v0_bridge/lowering/loop_.rs
  - sanitize: BTreeMap dedup + sort
  - optimize_same_value: check all inputs for same value
- Remove mod declaration in phi_core/mod.rs

Rationale:
- PhiInputCollector already inlined in Phase 59 (loopform_builder.rs)
- Last remaining usage was in JSON v0 Bridge
- Simple inline preserves exact behavior

Impact:
- -384 lines (Box + tests)
- No behavior change (inline equivalent)
- Build & test pass ✅

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

src/runner/json_v0_bridge/lowering/loop_.rs

@@ -25,7 +25,6 @@ use super::super::ast::StmtV0;
 use super::{lower_stmt_list_with_vars, new_block, BridgeEnv, LoopContext};
 use crate::ast::Span;
 use crate::mir::phi_core::loopform_builder::{LoopFormBuilder, LoopFormOps};
-use crate::mir::phi_core::phi_input_collector::PhiInputCollector;
 use crate::mir::{BasicBlockId, MirFunction, MirInstruction, ValueId};
 use std::collections::BTreeMap;
 
@@ -355,28 +354,42 @@ pub(super) fn lower_loop_stmt(
             }
 
             // 6-2) continue_merge_bb に必要な PHI を生成しつつ、merged_snapshot を作る
-            // Phase 26-B-3: Use PhiInputCollector
+            // Phase 62: PhiInputCollector インライン化
             let mut merged_snapshot: BTreeMap<String, ValueId> = BTreeMap::new();
             for (name, inputs) in all_inputs {
-                let mut collector = PhiInputCollector::new();
-                collector.add_snapshot(&inputs);
-                collector.sanitize();
+                // Inline PhiInputCollector logic
+                // 1. Sanitize: remove duplicates and sort
+                let mut seen: BTreeMap<BasicBlockId, ValueId> = BTreeMap::new();
+                for (bb, val) in inputs.iter() {
+                    seen.insert(*bb, *val);
+                }
+                let mut sanitized_inputs: Vec<(BasicBlockId, ValueId)> = seen.into_iter().collect();
+                sanitized_inputs.sort_by_key(|(bb, _)| bb.0);
 
-                let value = if let Some(same_val) = collector.optimize_same_value() {
-                    // 全て同じ値 or 単一入力 → PHI 不要
-                    same_val
+                // 2. Optimize: check if all inputs have the same value
+                let value = if sanitized_inputs.is_empty() {
+                    // Should not happen, but handle gracefully
+                    continue;
+                } else if sanitized_inputs.len() == 1 {
+                    // Single input - no PHI needed
+                    sanitized_inputs[0].1
                 } else {
-                    // 異なる値を持つ場合は PHI ノードを continue_merge_bb に生成
-                    let final_inputs = collector.finalize();
-                    let phi_id = ops.f.next_value_id();
-                    crate::mir::ssot::cf_common::insert_phi_at_head_spanned(
-                        ops.f,
-                        continue_merge_bb,
-                        phi_id,
-                        final_inputs,
-                        Span::unknown(),
-                    );
-                    phi_id
+                    let first_val = sanitized_inputs[0].1;
+                    if sanitized_inputs.iter().all(|(_, val)| *val == first_val) {
+                        // All same value - no PHI needed
+                        first_val
+                    } else {
+                        // Different values - PHI required
+                        let phi_id = ops.f.next_value_id();
+                        crate::mir::ssot::cf_common::insert_phi_at_head_spanned(
+                            ops.f,
+                            continue_merge_bb,
+                            phi_id,
+                            sanitized_inputs,
+                            Span::unknown(),
+                        );
+                        phi_id
+                    }
                 };
                 merged_snapshot.insert(name, value);
             }