move version extraction patterns to version.go and compile them at init
time instead of recompiling on every check. this significantly improves
framework detection performance.
- add version.go with pre-compiled regex patterns for all frameworks
- update detect.go to use extractVersionOptimized
- remove duplicate extractVersionWithConfidence and isValidVersion functions
- add io.LimitReader to prevent memory exhaustion on large responses
- update tests to use the optimized version extraction
