rolls the (c) 2022-2025 banner to 2022-2026 across all go files, the
startup banner in sif.go, and the header-check workflow's expected
format. comment-only, nothing else changes.
- create detector interface and registry for extensibility
- extract detectors to separate files: backend.go, frontend.go, cms.go, meta.go
- reduce detect.go from 785 lines to 178 lines (pure orchestrator)
- export VersionMatch and ExtractVersionOptimized for detector use
- create result.go with NewFrameworkResult and WithVulnerabilities helpers
- add url validation to New() for early error detection
- add sif_test.go with main package tests
- update detect_test.go to use external test package pattern
vmfunc