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.

tools/hako_check/render/graphviz.hako

@@ -7,6 +7,9 @@ static box GraphvizRenderBox {
   render_multi(irs) {
     // irs: ArrayBox of IR Map
     print("digraph Hako {")
+    // Internal key names for node/edge key lists (avoid collisions with user names)
+    local NK_KEY = "__graphviz_nodes__"
+    local EK_KEY = "__graphviz_edges__"
     // optional graph attributes (kept minimal)
     // print("  rankdir=LR;")
     // Node and edge sets to avoid duplicates
@@ -23,7 +26,8 @@ static box GraphvizRenderBox {
     // Build clusters by box: group nodes whose name looks like Box.method/arity
     local groups = new MapBox()
     local group_keys = new ArrayBox()
-    local nk = nodes.get("__keys__")
+    local nk = nodes.get(NK_KEY)
+    if nk == null { nk = new ArrayBox() }
     if nk != null {
       local i = 0
       while i < nk.size() {
@@ -60,7 +64,8 @@ static box GraphvizRenderBox {
       // edges map key = from + "\t" + to
       // naive iteration by trying to get keys from a stored list
       // We kept an ArrayBox under edges.get("__keys__") for listing
-      local ks = edges.get("__keys__")
+      local ks = edges.get(EK_KEY)
+      if ks == null { ks = new ArrayBox() }
       if ks != null {
         local ei = 0
         while ei < ks.size() {
@@ -119,7 +124,7 @@ static box GraphvizRenderBox {
     if name == null { return }
     nodes.set(name, 1)
     // also store a list of keys for emitting (since Map has no key iterator)
-    local arr = nodes.get("__keys__"); if arr == null { arr = new ArrayBox(); nodes.set("__keys__", arr) }
+    local arr = nodes.get("__graphviz_nodes__"); if arr == null { arr = new ArrayBox(); nodes.set("__graphviz_nodes__", arr) }
     // avoid duplicates
     local seen = 0
     local i = 0; while i < arr.size() { if arr.get(i) == name { seen = 1; break } i = i + 1 }
@@ -129,7 +134,7 @@ static box GraphvizRenderBox {
     if src == null || dst == null { return }
     local key = src + "\t" + dst
     if edges.get(key) == null { edges.set(key, 1) }
-    local arr = edges.get("__keys__"); if arr == null { arr = new ArrayBox(); edges.set("__keys__", arr) }
+    local arr = edges.get("__graphviz_edges__"); if arr == null { arr = new ArrayBox(); edges.set("__graphviz_edges__", arr) }
     // avoid duplicates
     local seen = 0
     local i = 0; while i < arr.size() { if arr.get(i) == key { seen = 1; break } i = i + 1 }