fix: Minor issues #12 and #13 - ASCII mode and performance optimization

This commit addresses the remaining Minor issues from PR #94 code review:

Minor #12: Unicode Symbol Compatibility
- Added CODEAGENT_ASCII_MODE environment variable support
- When set to "true", uses ASCII symbols: PASS/WARN/FAIL
- Default behavior (unset or "false"): Unicode symbols ✓/⚠️/✗
- Updated help text to document the environment variable
- Added tests for both ASCII and Unicode modes

Implementation:
- executor.go:514: New getStatusSymbols() function
- executor.go:531: Dynamic symbol selection in generateFinalOutputWithMode
- main.go:34: useASCIIMode variable declaration
- main.go:495: Environment variable documentation in help
- executor_concurrent_test.go:292: Tests for ASCII mode
- main_integration_test.go:89: Parser updated for both symbol formats

Minor #13: Performance Optimization - Reduce Repeated String Operations
- Optimized Message parsing to split only once per task result
- Added *FromLines() variants of all extractor functions
- Original extract*() functions now wrap *FromLines() for compatibility
- Reduces memory allocations and CPU usage in parallel execution

Implementation:
- utils.go:300: extractCoverageFromLines()
- utils.go:390: extractFilesChangedFromLines()
- utils.go:455: extractTestResultsFromLines()
- utils.go:551: extractKeyOutputFromLines()
- main.go:255: Single split with reuse: lines := strings.Split(...)

Backward Compatibility:
- All original extract*() functions preserved
- Tests updated to handle both symbol formats
- No breaking changes to public API

Test Results:
- All tests pass: go test ./... (40.164s)
- ASCII mode verified: PASS/WARN/FAIL symbols display correctly
- Unicode mode verified: ✓/⚠️/✗ symbols remain default
- Performance: Single split per Message instead of 4+

Usage Examples:
  # Unicode mode (default)
  ./codeagent-wrapper --parallel < tasks.txt

  # ASCII mode (for terminals without Unicode support)
  CODEAGENT_ASCII_MODE=true ./codeagent-wrapper --parallel < tasks.txt

Benefits:
- Improved terminal compatibility across different environments
- Reduced memory allocations in parallel execution
- Better performance for large-scale parallel tasks
- User choice between Unicode aesthetics and ASCII compatibility

Related: #94

Generated with SWE-Agent.ai

Co-Authored-By: SWE-Agent.ai <noreply@swe-agent.ai>

codeagent-wrapper/main.go

@@ -31,6 +31,8 @@ const (
 	stdoutDrainTimeout     = 100 * time.Millisecond
 )
 
+var useASCIIMode = os.Getenv("CODEAGENT_ASCII_MODE") == "true"
+
 // Test hooks for dependency injection
 var (
 	stdinReader  io.Reader = os.Stdin
@@ -257,18 +259,20 @@ func run() (exitCode int) {
 					continue
 				}
 
+				lines := strings.Split(results[i].Message, "\n")
+
 				// Coverage extraction
-				results[i].Coverage = extractCoverage(results[i].Message)
+				results[i].Coverage = extractCoverageFromLines(lines)
 				results[i].CoverageNum = extractCoverageNum(results[i].Coverage)
 
 				// Files changed
-				results[i].FilesChanged = extractFilesChanged(results[i].Message)
+				results[i].FilesChanged = extractFilesChangedFromLines(lines)
 
 				// Test results
-				results[i].TestsPassed, results[i].TestsFailed = extractTestResults(results[i].Message)
+				results[i].TestsPassed, results[i].TestsFailed = extractTestResultsFromLines(lines)
 
 				// Key output summary
-				results[i].KeyOutput = extractKeyOutput(results[i].Message, 150)
+				results[i].KeyOutput = extractKeyOutputFromLines(lines, 150)
 			}
 
 			// Default: summary mode (context-efficient)
@@ -487,7 +491,8 @@ Parallel mode examples:
     %[1]s --parallel <<'EOF'
 
 Environment Variables:
-    CODEX_TIMEOUT  Timeout in milliseconds (default: 7200000)
+    CODEX_TIMEOUT         Timeout in milliseconds (default: 7200000)
+    CODEAGENT_ASCII_MODE  Use ASCII symbols instead of Unicode (PASS/WARN/FAIL)
 
 Exit Codes:
     0    Success