refactor: upgrade to Go 1.26 and modernize code idioms

- Replace `interface{}` with `any` type alias across all packages
- Use built-in `min()`/`max()` for parameter clamping
- Use `slices.SortFunc`, `slices.Min`, `slices.Max` for cleaner code
- Use `strings.Cut()` for simpler string parsing in auth middleware
- Use `errors.Is()` for proper error comparison in handlers
- Update dependencies: golang.org/x/image 0.37.0 -> 0.38.0
- Add Wire code generation guidelines to ARCHITECTURE.md
- Disable Go cache in CI build workflow

internal/config/config.go

@@ -153,7 +153,7 @@ func Load(configPath string) (*Config, error) {
 	viper.SetDefault("hot_rank.recent_fetch_limit", 500)
 	viper.SetDefault("hot_rank.candidate_cap", 800)
 	// WebRTC 默认值（Google 公共 STUN 服务器）
-	viper.SetDefault("webrtc.ice_servers", []map[string]interface{}{
+	viper.SetDefault("webrtc.ice_servers", []map[string]any{
 		{"urls": []string{"stun:stun.l.google.com:19302"}},
 	})
 	// Report 默认值