feat: add DB_TIMEZONE configuration and update logging for PostgreSQL timezone

config/config.go

@@ -17,6 +17,7 @@ type Config struct {
 	RequestTimeoutSeconds int
 	OpenAIModel           string // default model when client omits it
 	Streaming             bool   // enable/disable SSE streaming responses
+	DBTimezone            string // PostgreSQL session timezone (e.g. "Europe/Istanbul")
 }
 
 // Load reads environment variables and returns a populated Config.
@@ -51,6 +52,7 @@ func Load() *Config {
 
 	openAIApiKey := os.Getenv("OPENAI_KEY")
 	openAIModel := os.Getenv("OPENAI_MODEL")
+	dbTimezone := os.Getenv("DB_TIMEZONE")
 
 	streaming := true
 	if v := os.Getenv("STREAMING"); v != "" {
@@ -70,5 +72,6 @@ func Load() *Config {
 		RequestTimeoutSeconds: timeoutSec,
 		OpenAIModel:           openAIModel,
 		Streaming:             streaming,
+		DBTimezone:            dbTimezone,
 	}
 }