fix: Phase 2 — HIGH #6,9,10,11,12,19,23,32,46,47

Files modified (5):
  compiler/gengo/gengo.go — #6,#32: Deduplicate 3 Generate functions into 1
    doGenerate(file, debug, library) replaces 170 lines of copy-paste
    Dead GenerateDebug method removed
  cmd/five/main.go — #9,10,11,12: Fix 5 silently ignored errors
    filepath.Abs, tidy.Run, tidyCmd.CombinedOutput now checked
  hbrtl/strings.go — #19: Str() now reads caller's nWidth/nDec params
    Was ignoring explicit Str(123, 10, 2) arguments
  compiler/pp/pp.go — #46: Fix stale "NOT implemented" comment
    #47: Extract maxIncludeDepth constant
  compiler/lexer/lexer.go — #23: Remove unused LookupKeyword result

Issues resolved: 10 (HIGH: 7, MEDIUM: 3)
Total fixed: 26/53

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

hbrtl/strings.go

@@ -15,7 +15,8 @@ import (
 // Str converts a numeric value to a string.
 // Harbour: Str(nValue [, nWidth [, nDec]]) → cString
 func Str(t *hbrt.Thread) {
-	t.Frame(1, 0) // at least 1 param
+	nParams := t.ParamCount()
+	t.Frame(nParams, 0)
 	defer t.EndProc()
 
 	v := t.Local(1)
@@ -26,9 +27,18 @@ func Str(t *hbrt.Thread) {
 	}
 
 	d := v.AsNumDouble()
+
+	// Width and decimals: use caller's args if provided, else Value metadata
 	width := int(v.Length())
 	dec := int(v.Decimal())
 
+	if nParams >= 2 && !t.Local(2).IsNil() {
+		width = t.Local(2).AsInt()
+	}
+	if nParams >= 3 && !t.Local(3).IsNil() {
+		dec = t.Local(3).AsInt()
+	}
+
 	if width == 0 || width == 255 {
 		width = 10 // default width
 	}