feat(joinir): Phase 76 - promoted_bindings map (dev-only)

Phase 76 introduces type-safe promotion tracking via promoted_bindings
(BindingId→BindingId map). Replaces fragile string matching hacks with
compiler-checked identity mapping.

Changes:
- carrier_info.rs: Added promoted_bindings field and resolution methods
- pattern4_carrier_analyzer.rs: Updated for BindingId integration
- pattern_pipeline.rs: Carrier resolution via promoted_bindings
- loop_with_break_minimal/tests.rs: Added promoted_bindings tests
- normalized/fixtures.rs: Extended with Phase 76 fixtures

Tests: 5/5 new unit tests PASS (record/resolve/merge/default/overwrite)
Tests: lib 958/958 PASS, normalized_dev 54/54 PASS (no regressions)

Design: Dual-path (BindingId OR name) enables gradual Phase 77+ transition.

🤖 Generated with Claude Code

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

src/mir/builder/control_flow/joinir/patterns/pattern4_carrier_analyzer.rs

@@ -71,6 +71,8 @@ impl Pattern4CarrierAnalyzer {
             carriers: updated_carriers,
             trim_helper: all_carriers.trim_helper.clone(),
             promoted_loopbodylocals: all_carriers.promoted_loopbodylocals.clone(), // Phase 224
+            #[cfg(feature = "normalized_dev")]
+            promoted_bindings: all_carriers.promoted_bindings.clone(), // Phase 76
         })
     }
 
@@ -294,6 +296,8 @@ mod tests {
             ],
             trim_helper: None,
             promoted_loopbodylocals: Vec::new(), // Phase 224
+            #[cfg(feature = "normalized_dev")]
+            promoted_bindings: std::collections::BTreeMap::new(), // Phase 76
         };
 
         // Analyze carriers

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

@@ -414,6 +414,8 @@ mod tests {
                 ],
                 trim_helper: None,
                 promoted_loopbodylocals: Vec::new(), // Phase 224
+                #[cfg(feature = "normalized_dev")]
+                promoted_bindings: std::collections::BTreeMap::new(), // Phase 76
             },
             loop_scope: LoopScopeShapeBuilder::empty_body_locals(
                 BasicBlockId(0),
@@ -453,6 +455,8 @@ mod tests {
                     whitespace_chars: vec![" ".to_string(), "\t".to_string()],
                 }),
                 promoted_loopbodylocals: Vec::new(), // Phase 224
+                #[cfg(feature = "normalized_dev")]
+                promoted_bindings: std::collections::BTreeMap::new(), // Phase 76
             },
             loop_scope: LoopScopeShapeBuilder::empty_body_locals(
                 BasicBlockId(0),