feat: SET commands + ErrorBlock/Break error handling

SET commands (setcmd.go):
  - SetDateFunc: __SetDateFormat([cNew]) → cOld
  - SetDecimalsFunc: SET DECIMALS TO n
  - SetEpochFunc: SET EPOCH TO n
  - 11 toggle functions: SetExact, SetDeleted, SetSoftSeek, SetExclusive,
    SetFixed, SetCancel, SetBell, SetConfirm, SetInsert, SetEscape, SetWrap
  - SET constants: _SET_EXACT, _SET_DELETED, etc. for PRG code
  - GetSetDateFormat(), GetSetDecimals(), GetSetEpoch() helpers
  - Default: DATE="mm/dd/yy", EPOCH=1900, DECIMALS=2

Error handling (error.go):
  - Break(xValue): panics with BreakValue, caught by BEGIN SEQUENCE
  - BreakBlock(): returns {|e| Break(e)} code block
  - LaunchError(): dispatches error through ErrorBlock handler
  - RuntimeError(): creates + launches standard runtime error
  - IsBreak(): checks if recovered panic is a BreakValue
  - createErrorHash(): builds Harbour-compatible error hash

Registration: ErrorBlock, ErrorNew, DosError, FError, Break + all SET functions

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

docs/.pdca-status.json

@@ -1,6 +1,6 @@
 {
   "version": "2.0",
-  "lastUpdated": "2026-04-02T06:00:35.695Z",
+  "lastUpdated": "2026-04-02T06:32:27.120Z",
   "activeFeatures": [
     "hbrt",
     "hbrtl",
@@ -46,9 +46,9 @@
       "documents": {},
       "timestamps": {
         "started": "2026-03-27T11:15:10.675Z",
-        "lastUpdated": "2026-04-01T02:36:49.307Z"
+        "lastUpdated": "2026-04-02T06:32:27.120Z"
       },
-      "lastFile": "/mnt/d/charles/five/hbrtl/strings.go"
+      "lastFile": "/mnt/d/charles/five/hbrtl/missing.go"
     },
     "tests": {
       "phase": "do",
@@ -280,7 +280,7 @@
   "session": {
     "startedAt": "2026-03-27T06:06:49.620Z",
     "onboardingCompleted": false,
-    "lastActivity": "2026-04-02T06:00:35.695Z"
+    "lastActivity": "2026-04-02T06:32:27.120Z"
   },
   "history": [
     {
@@ -5952,6 +5952,36 @@
       "feature": "hbrt",
       "phase": "do",
       "action": "updated"
+    },
+    {
+      "timestamp": "2026-04-02T06:27:16.050Z",
+      "feature": "hbrtl",
+      "phase": "do",
+      "action": "updated"
+    },
+    {
+      "timestamp": "2026-04-02T06:27:58.417Z",
+      "feature": "hbrtl",
+      "phase": "do",
+      "action": "updated"
+    },
+    {
+      "timestamp": "2026-04-02T06:29:57.154Z",
+      "feature": "hbrtl",
+      "phase": "do",
+      "action": "updated"
+    },
+    {
+      "timestamp": "2026-04-02T06:30:58.549Z",
+      "feature": "hbrtl",
+      "phase": "do",
+      "action": "updated"
+    },
+    {
+      "timestamp": "2026-04-02T06:32:27.120Z",
+      "feature": "hbrtl",
+      "phase": "do",
+      "action": "updated"
     }
   ]
 }