refactor(log): migrate from zerolog to structured slog with bridge

- Replace direct zerolog usage with standard library `log/slog` in business code
- Add `internal/logging` package with zerolog bridge handler for structured output
- Create `internal/jsoncodec` package to centralize JSON encoding/decoding using Sonic
- Update all services and main entry point to use new logging interface
- Maintain backward compatibility with existing zerolog console output
- Remove custom logger setup in favor of structured logging bridge

internal/jsoncodec/jsoncodec.go

@@ -0,0 +1,17 @@
+package jsoncodec
+
+import (
+	"io"
+
+	"github.com/bytedance/sonic"
+)
+
+func Marshal(v any) ([]byte, error) { return sonic.Marshal(v) }
+
+func Unmarshal(data []byte, v any) error { return sonic.Unmarshal(data, v) }
+
+func UnmarshalString(data string, v any) error { return sonic.UnmarshalString(data, v) }
+
+func NewEncoder(w io.Writer) sonic.Encoder { return sonic.ConfigDefault.NewEncoder(w) }
+
+func NewDecoder(r io.Reader) sonic.Decoder { return sonic.ConfigDefault.NewDecoder(r) }