trace: add execution route visibility + debug passthrough; phase2170 canaries; docs

- Add HAKO_TRACE_EXECUTION to trace executor route
  - Rust hv1_inline: stderr [trace] executor: hv1_inline (rust)
  - Hakovm dispatcher: stdout [trace] executor: hakovm (hako)
  - test_runner: trace lines for hv1_inline/core/hakovm routes
- Add HAKO_VERIFY_SHOW_LOGS and HAKO_DEBUG=1 (enables both)
  - verify_v1_inline_file() log passthrough with numeric rc extraction
  - test_runner exports via HAKO_DEBUG
- Canary expansion under phase2170 (state spec)
  - Array: push×5/10 → size, len/length alias, per‑recv/global, flow across blocks
  - Map: set dup-key non-increment, value_state get/has
  - run_all.sh: unify, remove SKIPs; all PASS
- Docs
  - ENV_VARS.md: add Debug/Tracing toggles and examples
  - PLAN.md/CURRENT_TASK.md: mark 21.7 green, add Quickstart lines

All changes gated by env vars; default behavior unchanged.

lang/src/vm/hakorune-vm/dispatcher_v1.hako

@@ -164,6 +164,7 @@ static box NyVmDispatcherV1Box {
   }
   // Main entry: Choose internal scanner when enabled; otherwise delegate to Mini‑VM
   run(json) {
+    if env.get("HAKO_TRACE_EXECUTION") == "1" { print("[trace] executor: hakovm (hako)") }
     // Typed IR primary (限定): 構造IR生成を有効化しつつ既存フローを使用（挙動不変）
     if env.get("HAKO_V1_TYPED_IR_PRIMARY") == "1" {
       // ShadowをONにして構造IR生成のオーバーヘッドを観測（必要時）