feat(llvm): Phase 132-P0 - block_end_values tuple-key fix for cross-function isolation

## Problem
`block_end_values` used block ID only as key, causing collisions when
multiple functions share the same block IDs (e.g., bb0 in both
condition_fn and main).

## Root Cause
- condition_fn's bb0 → block_end_values[0]
- main's bb0 → block_end_values[0] (OVERWRITES!)
- PHI resolution gets wrong snapshot → dominance error

## Solution (Box-First principle)
Change key from `int` to `Tuple[str, int]` (func_name, block_id):

```python
# Before
block_end_values: Dict[int, Dict[int, ir.Value]]

# After
block_end_values: Dict[Tuple[str, int], Dict[int, ir.Value]]
```

## Files Modified (Python - 6 files)

1. `llvm_builder.py` - Type annotation update
2. `function_lower.py` - Pass func_name to lower_blocks
3. `block_lower.py` - Use tuple keys for snapshot save/load
4. `resolver.py` - Add func_name parameter to resolve_incoming
5. `wiring.py` - Thread func_name through PHI wiring
6. `phi_manager.py` - Debug traces

## Files Modified (Rust - cleanup)

- Removed deprecated `loop_to_join.rs` (297 lines deleted)
- Updated pattern lowerers for cleaner exit handling
- Added lifecycle management improvements

## Verification

- ✅ Pattern 1: VM RC: 3, LLVM Result: 3 (no regression)
- ⚠️ Case C: Still has dominance error (separate root cause)
  - Needs additional scope fixes (phi_manager, resolver caches)

## Design Principles

- **Box-First**: Each function is an isolated Box with scoped state
- **SSOT**: (func_name, block_id) uniquely identifies block snapshots
- **Fail-Fast**: No cross-function state contamination

## Known Issues (Phase 132-P1)

Other function-local state needs same treatment:
- phi_manager.predeclared
- resolver caches (i64_cache, ptr_cache, etc.)
- builder._jump_only_blocks

## Documentation

- docs/development/current/main/investigations/phase132-p0-case-c-root-cause.md
- docs/development/current/main/investigations/phase132-p0-tuple-key-implementation.md

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

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

src/llvm_py/phi_manager.py

@@ -25,6 +25,7 @@ class PhiManager:
         """Filter vmap while preserving owned PHIs
 
         SSOT: PHIs in vmap are the single source of truth
+        Phase 132-P0: Also add PHIs from predeclared registry
         """
         result = {}
         for vid, val in vmap.items():
@@ -33,6 +34,12 @@ class PhiManager:
                     result[vid] = val
             else:
                 result[vid] = val
+
+        # Phase 132-P0: Add PHIs from predeclared that aren't in vmap yet
+        for (bid, vid), phi_val in self.predeclared.items():
+            if bid == target_bid and vid not in result:
+                result[vid] = phi_val
+
         return result
 
     def sync_protect_phis(self, target_vmap: dict, source_vmap: dict):