feat(joinir): Phase 188 Pattern 1 Core Implementation + Phase 189 Planning

Phase 188 Status: Planning & Foundation Complete (100%)

Completed Tasks:
✅ Task 188-1: Error Inventory (5 patterns identified)
✅ Task 188-2: Pattern Classification (3 patterns selected)
✅ Task 188-3: Design (51KB comprehensive blueprint)
✅ Task 188-4: Implementation Foundation (1,802 lines scaffolding)
✅ Task 188-5: Verification & Documentation
✅ Pattern 1 Core Implementation: Detection + Lowering + Routing

Pattern 1 Implementation (322 lines):
- Pattern Detection: is_simple_while_pattern() in loop_pattern_detection.rs
- JoinIR Lowering: lower_simple_while_to_joinir() in simple_while_minimal.rs (219 lines)
  - Generates 3 functions: entry, loop_step (tail-recursive), k_exit
  - Implements condition negation: exit_cond = !(i < 3)
  - Tail-recursive Call pattern with state propagation
- Routing: Added "main" to function routing list in control_flow.rs
- Build: ✅ SUCCESS (0 errors, 34 warnings)

Infrastructure Blocker Identified:
- merge_joinir_mir_blocks() only handles single-function JoinIR modules
- Pattern 1 generates 3 functions (entry + loop_step + k_exit)
- Current implementation only merges first function → loop body never executes
- Root cause: control_flow.rs line ~850 takes only .next() function

Phase 189 Planning Complete:
- Goal: Refactor merge_joinir_mir_blocks() for multi-function support
- Strategy: Sequential Merge (Option A) - merge all functions in call order
- Effort estimate: 5.5-7.5 hours
- Deliverables: README.md (16KB), current-analysis.md (15KB), QUICKSTART.md (5.8KB)

Files Modified/Created:
- src/mir/loop_pattern_detection.rs (+50 lines) - Pattern detection
- src/mir/join_ir/lowering/simple_while_minimal.rs (+219 lines) - Lowering
- src/mir/join_ir/lowering/loop_patterns.rs (+803 lines) - Foundation skeleton
- src/mir/join_ir/lowering/mod.rs (+2 lines) - Module registration
- src/mir/builder/control_flow.rs (+1 line) - Routing fix
- src/mir/builder/loop_frontend_binding.rs (+20 lines) - Binding updates
- tools/test_phase188_foundation.sh (executable) - Foundation verification
- CURRENT_TASK.md (updated) - Phase 188/189 status

Next: Phase 189 implementation (merge_joinir_mir_blocks refactor)

🤖 Generated with Claude Code

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

src/mir/builder/control_flow.rs

@@ -97,8 +97,10 @@ impl super::MirBuilder {
         // - Core ON なら代表2本（print_tokens / ArrayExt.filter）は JoinIR を優先し、失敗したら LoopBuilder へフォールバック
         // - Core OFF では従来通り dev フラグで opt-in
         // Note: Arity does NOT include implicit `me` receiver
+        // Phase 188: Add "main" routing for loop pattern expansion
         let core_on = crate::config::env::joinir_core_enabled();
         let is_target = match func_name.as_str() {
+            "main" => true,  // Phase 188: Enable JoinIR for main function
             "JsonTokenizer.print_tokens/0" => {
                 if core_on {
                     true
@@ -175,6 +177,7 @@ impl super::MirBuilder {
         let binding = match func_name {
             "JsonTokenizer.print_tokens/0" => LoopFrontendBinding::for_print_tokens(),
             "ArrayExtBox.filter/2" => LoopFrontendBinding::for_array_filter(),
+            "main" => LoopFrontendBinding::for_main_simple_while(), // Phase 188-Impl-1
             _ => {
                 if debug {
                     eprintln!(