fix(normalization): Phase 143 execution fix - Param region SSOT

Problem: normalized_helpers allocated env params as ValueId(1,2...)
in PHI Reserved region (0-99) instead of Param region (100-999)
per JoinValueSpace contract.

Root cause: All 4 normalized shadow modules started from
next_value_id=1, violating the Param region contract.

Solution:
- Add NormalizedHelperBox::alloc_env_params_param_region()
  that allocates params starting from PARAM_MIN (100)
- Update 4 normalized shadow files to use new API:
  - loop_true_if_break_continue.rs
  - loop_true_break_once.rs
  - if_as_last_join_k.rs
  - post_if_post_k.rs
- Fix instruction_rewriter.rs type mismatch
  (func.signature.params → func.params)

Verification:
- Unit tests: 69/69 PASS
- VM smoke: exit code 7 ✅
- LLVM EXE smoke: exit code 7 ✅ (timeout resolved!)

ValueId Space Contract (Phase 201):
| Region       | Range    | Purpose                      |
|--------------|----------|------------------------------|
| PHI Reserved | 0-99     | Loop header PHI dst          |
| Param        | 100-999  | env params (flag, counter)   |
| Local        | 1000+    | Const, BinOp, condition      |

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

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

docs/development/current/main/design/normalized-expr-lowering.md

@@ -191,3 +191,58 @@ let available_inputs = AvailableInputsCollectorBox::collect(
 ### Diagnostics
 
 - `OutOfScopeReason::IntrinsicNotWhitelisted` を追加し、`MethodCall` の out-of-scope 理由を精密化する。
+
+---
+
+## ValueId Space Contract (Phase 143 fix)
+
+### 問題
+
+Normalized shadow modules allocate env params using `alloc_value_id()` starting from 1, but JoinValueSpace contract requires Param region (100-999).
+
+**Wrong** (before fix):
+```rust
+let mut next_value_id: u32 = 1;
+let params = NormalizedHelperBox::alloc_env_params(&fields, &mut next_value_id);
+// → [ValueId(1), ValueId(2), ...] — PHI Reserved region!
+```
+
+**Correct** (after fix):
+```rust
+let (params, mut next_local) = NormalizedHelperBox::alloc_env_params_param_region(&fields);
+// → [ValueId(100), ValueId(101), ...] — Param region ✅
+```
+
+### Contract (Phase 201 SSOT)
+
+```
+ 0          100        1000                     u32::MAX
+ ├──────────┼──────────┼──────────────────────────┤
+ │  PHI     │  Param   │       Local             │
+ │  Reserved│  Region  │       Region            │
+ └──────────┴──────────┴──────────────────────────┘
+```
+
+| Region | Range | Purpose |
+|--------|-------|---------|
+| PHI Reserved | 0-99 | Loop header PHI dst |
+| **Param** | **100-999** | **env params (flag, counter, etc.)** |
+| Local | 1000+ | Const, BinOp, condition results |
+
+### SSOT
+
+- Constants: `src/mir/join_ir/lowering/join_value_space.rs`
+  - `PARAM_MIN = 100`
+  - `LOCAL_MIN = 1000`
+- API: `NormalizedHelperBox::alloc_env_params_param_region()`
+  - Location: `src/mir/control_tree/normalized_shadow/common/normalized_helpers.rs`
+  - Returns: `(Vec<ValueId>, u32)` — (params in 100+ range, next_local starting at 1000)
+
+### Affected Files
+
+- `loop_true_if_break_continue.rs`
+- `loop_true_break_once.rs`
+- `if_as_last_join_k.rs`
+- `post_if_post_k.rs`
+
+All normalized shadow modules must use `alloc_env_params_param_region()` instead of `alloc_env_params()` to ensure env params are in the correct region.