feat(joinir): Phase 192-impl ComplexAddendNormalizer implementation

- New module: complex_addend_normalizer.rs (320 lines, 5 unit tests)
- Transforms `result = result * 10 + f(x)` into temp variable pattern
- Pattern2 preprocessing integration (~40 lines added)
- Zero changes to emission layers (reuses Phase 191 + Phase 190)

Tests:
- Unit tests: 5/5 passing (normalization logic)
- Regression: phase190/191 tests all pass
- Demo: phase192_normalization_demo.hako → 123

Limitation: Full E2E requires Phase 193 (MethodCall in init)

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

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

src/mir/builder/control_flow/joinir/patterns/pattern2_with_break.rs

@@ -240,9 +240,43 @@ impl MirBuilder {
             break_condition_node.clone()
         };
 
+        // Phase 192: Normalize complex addend patterns in loop body
+        // This transforms patterns like `result = result * 10 + digits.indexOf(ch)`
+        // into `local temp = digits.indexOf(ch); result = result * 10 + temp`
+        use crate::mir::join_ir::lowering::complex_addend_normalizer::{
+            ComplexAddendNormalizer, NormalizationResult
+        };
+
+        let mut normalized_body = Vec::new();
+        let mut has_normalization = false;
+
+        for node in _body {
+            match ComplexAddendNormalizer::normalize_assign(node) {
+                NormalizationResult::Normalized { temp_def, new_assign, temp_name } => {
+                    eprintln!(
+                        "[pattern2/phase192] Normalized complex addend: temp='{}' inserted before update",
+                        temp_name
+                    );
+                    normalized_body.push(temp_def);
+                    normalized_body.push(new_assign);
+                    has_normalization = true;
+                }
+                NormalizationResult::Unchanged => {
+                    normalized_body.push(node.clone());
+                }
+            }
+        }
+
+        // Use normalized body for analysis (only if normalization occurred)
+        let analysis_body = if has_normalization {
+            &normalized_body
+        } else {
+            _body
+        };
+
         // Phase 176-3: Analyze carrier updates from loop body
         use crate::mir::join_ir::lowering::loop_update_analyzer::LoopUpdateAnalyzer;
-        let carrier_updates = LoopUpdateAnalyzer::analyze_carrier_updates(_body, &carrier_info.carriers);
+        let carrier_updates = LoopUpdateAnalyzer::analyze_carrier_updates(analysis_body, &carrier_info.carriers);
 
         eprintln!(
             "[cf_loop/pattern2] Phase 176-3: Analyzed {} carrier updates",
@@ -304,7 +338,7 @@ impl MirBuilder {
             &env,
             &carrier_info,
             &carrier_updates,
-            _body,  // Phase 191: Pass body AST for init lowering
+            analysis_body,  // Phase 191/192: Pass normalized body AST for init lowering
             Some(&mut body_local_env),  // Phase 191: Pass mutable body-local environment
         ) {
             Ok((module, meta)) => (module, meta),