feat: Value type methods — chain calls on String/Array/Numeric/Hash

Built-in methods on basic types, enabling fluent chaining:
  cStr:Trim():Upper():Left(5)    → "HELLO"
  aArr:Sort():Join(",")          → "1,2,3"

String (20 methods):
  Upper, Lower, Trim, LTrim, RTrim, Left, Right, Substr,
  Len, Replace, Split, Contains, Starts, Ends, Reverse,
  Replicate, Copy, At, Empty, Val

Array (14 methods):
  Len, Push, Pop, Sort, Find, Map, Filter, Each,
  Join, Copy, Empty, First, Last, Slice

Numeric (6 methods):
  Str, Round, Int, Abs, Sqrt, Copy

Hash (7 methods):
  Keys, Values, Has, Len, Copy, Delete, Empty

Any type (5 methods):
  Copy, Type, IsNil, ToStr, ClassName

Integration: Thread.Send() checks SendBuiltin() before class dispatch.
Tests: 28 tests ALL PASS including chaining test.

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

docs/.pdca-status.json

@@ -1,6 +1,6 @@
 {
   "version": "2.0",
-  "lastUpdated": "2026-04-01T12:09:42.812Z",
+  "lastUpdated": "2026-04-02T03:31:23.903Z",
   "activeFeatures": [
     "hbrt",
     "hbrtl",
@@ -33,9 +33,9 @@
       "documents": {},
       "timestamps": {
         "started": "2026-03-27T09:33:04.512Z",
-        "lastUpdated": "2026-04-01T12:08:54.344Z"
+        "lastUpdated": "2026-04-02T03:31:23.903Z"
       },
-      "lastFile": "/mnt/d/charles/five/hbrt/frb.go"
+      "lastFile": "/mnt/d/charles/five/hbrt/valuemethods_test.go"
     },
     "hbrtl": {
       "phase": "do",
@@ -280,7 +280,7 @@
   "session": {
     "startedAt": "2026-03-27T06:06:49.620Z",
     "onboardingCompleted": false,
-    "lastActivity": "2026-04-01T12:09:42.812Z"
+    "lastActivity": "2026-04-02T03:31:23.903Z"
   },
   "history": [
     {
@@ -5880,6 +5880,24 @@
       "feature": "five",
       "phase": "do",
       "action": "updated"
+    },
+    {
+      "timestamp": "2026-04-02T03:29:33.962Z",
+      "feature": "hbrt",
+      "phase": "do",
+      "action": "updated"
+    },
+    {
+      "timestamp": "2026-04-02T03:30:25.427Z",
+      "feature": "hbrt",
+      "phase": "do",
+      "action": "updated"
+    },
+    {
+      "timestamp": "2026-04-02T03:31:23.903Z",
+      "feature": "hbrt",
+      "phase": "do",
+      "action": "updated"
     }
   ]
 }