test: Phase 117 if-only nested-if call merge parity (VM + LLVM EXE)

Fixture & Smoke tests for nested if-only with call merge verification.

**Fixture**:
- apps/tests/phase117_if_only_nested_if_call_merge_min.hako
- Pattern: nested if (inner: b == 1) inside outer if (a == 1), outer else
- Call merge: f(1), f(2), f(3) results merged to single variable v
- Expected output: 2, 3, 4 (f(x) = x + 1)

**VM Smoke**:
- tools/smokes/v2/profiles/integration/apps/phase117_if_only_nested_if_call_merge_vm.sh
- Execution: NYASH_DISABLE_PLUGINS=1 HAKO_JOINIR_STRICT=1
- Validation: numeric output 3 lines "2\n3\n4"

**LLVM EXE Smoke**:
- tools/smokes/v2/profiles/integration/apps/phase117_if_only_nested_if_call_merge_llvm_exe.sh
- Required plugins: FileBox, MapBox, StringBox, ConsoleBox, IntegerBox
- Validation: numeric output "2\n3\n4" (3 lines)

**Verification**:
✅ VM smoke: PASS
✅ LLVM EXE smoke: PASS
✅ Regression (Phase 116): PASS

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

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

apps/tests/phase117_if_only_nested_if_call_merge_min.hako

@@ -0,0 +1,18 @@
+static box Main {
+    f(x) { return x + 1 }
+    g(a, b) {
+        local v = 0
+        if a == 1 {
+            if b == 1 { v = f(1) } else { v = f(2) }
+        } else {
+            v = f(3)
+        }
+        print(v)
+    }
+    main() {
+        g(1, 1)  // → 2 (f(1) = 1+1)
+        g(1, 0)  // → 3 (f(2) = 2+1)
+        g(0, 0)  // → 4 (f(3) = 3+1)
+        return "OK"
+    }
+}