fix(circuit-breaker): eliminate JSON field false positives in error detection

Fixes circuit breaker opening prematurely due to naive error pattern matching
that treated JSON field names like "is_error": false as actual errors.

Changes:
- ralph_loop.sh: Implement two-stage error detection with JSON filtering
- lib/response_analyzer.sh: Apply same filtering to error counting
- tests/test_error_detection.sh: Add comprehensive test suite (12 scenarios)

Error detection now:
- Filters out JSON field patterns before searching for errors
- Uses context-specific patterns (^Error:, ]: error, Exception, Fatal)
- Avoids type annotations (error: Error) and code identifiers
- Includes debug logging when VERBOSE_PROGRESS=true

Test coverage validates:
✓ JSON fields don't trigger false positives
✓ Real error messages are correctly detected
✓ Mixed content handled properly
✓ Code diffs and documentation excluded

This prevents the consecutive_same_error counter from incrementing on
false positives, eliminating unnecessary circuit breaker trips.

ralph_loop.sh

@@ -386,8 +386,25 @@ EOF
             # Get file change count for circuit breaker
             local files_changed=$(git diff --name-only 2>/dev/null | wc -l || echo 0)
             local has_errors="false"
-            if grep -q "error\|Error\|ERROR" "$output_file"; then
+
+            # Two-stage error detection to avoid JSON field false positives
+            # Stage 1: Filter out JSON field patterns like "is_error": false
+            # Stage 2: Look for actual error messages in specific contexts
+            # Avoid type annotations like "error: Error" by requiring lowercase after ": error"
+            if grep -v '"[^"]*error[^"]*":' "$output_file" 2>/dev/null | \
+               grep -qE '(^Error:|^ERROR:|^error:|\]: error|Link: error|Error occurred|failed with error|[Ee]xception|Fatal|FATAL)'; then
                 has_errors="true"
+
+                # Debug logging: show what triggered error detection
+                if [[ "$VERBOSE_PROGRESS" == "true" ]]; then
+                    log_status "DEBUG" "Error patterns found:"
+                    grep -v '"[^"]*error[^"]*":' "$output_file" 2>/dev/null | \
+                        grep -nE '(^Error:|^ERROR:|^error:|\]: error|Link: error|Error occurred|failed with error|[Ee]xception|Fatal|FATAL)' | \
+                        head -3 | while IFS= read -r line; do
+                        log_status "DEBUG" "  $line"
+                    done
+                fi
+
                 log_status "WARN" "Errors detected in output, check: $output_file"
             fi
             local output_length=$(wc -c < "$output_file" 2>/dev/null || echo 0)