fix: Phase 1 Step 0 cleanup + CRITICAL #3, MEDIUM #36-37, LOW #50

Files modified (5):
  hbrt/macro.go — Replace hand-rolled parseFloat/parseInt64 with strconv (#50)
                   Remove stale TODO, redundant TrimSpace
  hbrt/macroeval.go — Use strconv for literal parsing (was using removed functions)
  hbrt/class.go — CRITICAL #3: Change RWMutex to Mutex on classList
                   Prevents slice reallocation race on concurrent GetClass
  hbrt/goroutine.go — #36: Channel double-close protection (sync.Once)
                       #37: Send on closed channel recovery (defer/recover)
                       Add IsClosed(), safe Receive (handles closed channel)
  hbrt/gobridge.go — Already clean (confirmed)
  hbrt/hbfunc.go — Already clean (confirmed)

Issues resolved: #3 (CRITICAL), #36, #37 (MEDIUM), #50 (LOW)
Total fixed: 16/53

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

docs/.pdca-status.json

@@ -1,6 +1,6 @@
 {
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-  "lastUpdated": "2026-04-01T01:30:25.114Z",
+  "lastUpdated": "2026-04-01T01:50:29.561Z",
   "activeFeatures": [
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     "hbrtl",
@@ -33,7 +33,7 @@
       "documents": {},
       "timestamps": {
         "started": "2026-03-27T09:33:04.512Z",
-        "lastUpdated": "2026-04-01T01:30:25.114Z"
+        "lastUpdated": "2026-04-01T01:50:29.560Z"
       },
       "lastFile": "/mnt/d/charles/five/hbrt/macroeval.go"
     },
@@ -280,7 +280,7 @@
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     "startedAt": "2026-03-27T06:06:49.620Z",
     "onboardingCompleted": false,
-    "lastActivity": "2026-04-01T01:30:25.114Z"
+    "lastActivity": "2026-04-01T01:50:29.561Z"
   },
   "history": [
     {
@@ -5568,6 +5568,66 @@
       "feature": "hbrt",
       "phase": "do",
       "action": "updated"
+    },
+    {
+      "timestamp": "2026-04-01T01:36:41.982Z",
+      "feature": "hbrt",
+      "phase": "do",
+      "action": "updated"
+    },
+    {
+      "timestamp": "2026-04-01T01:36:51.948Z",
+      "feature": "hbrt",
+      "phase": "do",
+      "action": "updated"
+    },
+    {
+      "timestamp": "2026-04-01T01:37:05.337Z",
+      "feature": "hbrt",
+      "phase": "do",
+      "action": "updated"
+    },
+    {
+      "timestamp": "2026-04-01T01:39:24.247Z",
+      "feature": "hbrt",
+      "phase": "do",
+      "action": "updated"
+    },
+    {
+      "timestamp": "2026-04-01T01:40:12.339Z",
+      "feature": "hbrt",
+      "phase": "do",
+      "action": "updated"
+    },
+    {
+      "timestamp": "2026-04-01T01:40:25.832Z",
+      "feature": "hbrt",
+      "phase": "do",
+      "action": "updated"
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+      "timestamp": "2026-04-01T01:42:45.339Z",
+      "feature": "hbrt",
+      "phase": "do",
+      "action": "updated"
+    },
+    {
+      "timestamp": "2026-04-01T01:43:04.161Z",
+      "feature": "hbrt",
+      "phase": "do",
+      "action": "updated"
+    },
+    {
+      "timestamp": "2026-04-01T01:50:06.804Z",
+      "feature": "hbrt",
+      "phase": "do",
+      "action": "updated"
+    },
+    {
+      "timestamp": "2026-04-01T01:50:29.561Z",
+      "feature": "hbrt",
+      "phase": "do",
+      "action": "updated"
     }
   ]
 }