Phase 21.7 normalization: optimization pre-work + bench harness expansion

- Add opt-in optimizations (defaults OFF)
  - Ret purity verifier: NYASH_VERIFY_RET_PURITY=1
  - strlen FAST enhancement for const handles
  - FAST_INT gate for same-BB SSA optimization
  - length cache for string literals in llvmlite
- Expand bench harness (tools/perf/microbench.sh)
  - Add branch/call/stringchain/arraymap/chip8/kilo cases
  - Auto-calculate ratio vs C reference
  - Document in benchmarks/README.md
- Compiler health improvements
  - Unify PHI insertion to insert_phi_at_head()
  - Add NYASH_LLVM_SKIP_BUILD=1 for build reuse
- Runtime & safety enhancements
  - Clarify Rust/Hako ownership boundaries
  - Strengthen receiver localization (LocalSSA/pin/after-PHIs)
  - Stop excessive PluginInvoke→BoxCall rewrites
- Update CURRENT_TASK.md, docs, and canaries

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

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

docs/development/roadmap/phases/phase-21.7-normalization/CHECKLIST.md

@@ -9,12 +9,15 @@ Targets (must be green)
 
 Canaries
 - tools/dev/phase216_chain_canary_call.sh — remains PASS when OFF, PASS when ON
-- Add: tools/dev/phase217_methodize_canary.sh (dev) — asserts method callee usage in MIR or IR tags
+- tools/dev/phase217_methodize_canary.sh (dev) — compile-run rc=5（セマンティクス）
+- tools/dev/phase217_methodize_json_canary.sh (dev) — v1 root（schema_version）+ mir_call present（Methodが望ましい、Globalは経過容認）
 
 Toggles
 - HAKO_MIR_BUILDER_METHODIZE=1 (new)
 - HAKO_STAGEB_FUNC_SCAN=1 / HAKO_MIR_BUILDER_FUNCS=1 / HAKO_MIR_BUILDER_CALL_RESOLVE=1 (existing)
+- 一軍（devプロファイルで既定ON）: 上記3つ + NYASH_JSON_SCHEMA_V1=1 + NYASH_MIR_UNIFIED_CALL=1
+- 診断（既定OFF）: HAKO_BRIDGE_METHODIZE=1（core_bridge側の補助。Hako既定化後に撤去）
 
 Rollback
 - Disable HAKO_MIR_BUILDER_METHODIZE; remove methodization rewrite; keep Global path active.
-
+ - core_bridgeの methodize ブリッジは Hako側が既定化され次第、撤去（タグ: [bridge/methodize:*] を一時観測可能にして差分検知）