test(smoke): Phase 283 P0 - Add VM/LLVM smoke tests + doc update

- VM smoke: phase283_p0_loop_if_phi_vm.sh (checks sum=9 output)
- LLVM smoke: phase283_p0_loop_if_phi_llvm.sh (checks Result: 0, exit=0)
- Documentation: Update phase-283 README with LLVM harness notes
  - LLVM harness suppresses program stdout
  - VM shows stdout, LLVM checks exit code only

Both tests verified: ✅ PASS

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

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

docs/development/current/main/phases/phase-283/README.md

@@ -45,3 +45,11 @@ After Phase 275 (C2), implicit `"String" + Integer` is a TypeError. The fixture
 
 - `apps/tests/loop_if_phi.hako` runs on VM without undefined ValueId errors and prints `sum=9`.
 
+Recommended smoke checks:
+- VM: `tools/smokes/v2/profiles/integration/apps/phase283_p0_loop_if_phi_vm.sh`
+  - Checks stdout output: `sum=9`
+  - Exit code: 0
+- LLVM harness: `tools/smokes/v2/profiles/integration/apps/phase283_p0_loop_if_phi_llvm.sh`
+  - **Note**: LLVM harness (`NYASH_LLVM_USE_HARNESS=1`) suppresses program stdout
+  - Only check: `Result: 0` line in stderr (exit code = 0)
+  - Direct execution: `NYASH_LLVM_USE_HARNESS=1 ./target/release/hakorune --backend llvm apps/tests/loop_if_phi.hako`