Add frontend pages, move static to www/, add resolution to tester

Frontend:
- index.html: probe device, navigate to standard/homekit by type
- standard.html: camera config, model search with multi-select
- create.html: stream URL list, custom URL input, create test session
- homekit.html: HomeKit device info, contact links, fallback to standard

Backend:
- Move static files to www/ package with embed (go2rtc pattern)
- Add initStatic() in api with FileServer
- Add width/height to test results from H264 SPS parsing
- Contribute links to gostrix.github.io with auto-filled params

pkg/tester/session.go

@@ -27,6 +27,8 @@ type Result struct {
 	Source     string   `json:"source"`
 	Screenshot string   `json:"screenshot,omitempty"`
 	Codecs     []string `json:"codecs,omitempty"`
+	Width      uint16   `json:"width,omitempty"`
+	Height     uint16   `json:"height,omitempty"`
 	LatencyMs  int64    `json:"latency_ms,omitempty"`
 	Skipped    bool     `json:"skipped,omitempty"`
 }