refactor(config): move Config struct from business layer to platform/config

Moved the Config struct (previously in internal/models/config.go) into internal/platform/config/types.go to align with clean architecture principles.

This change decouples runtime/infrastructure configuration from domain models:
- Configuration is an application/platform concern, not part of the business domain.
- Prevents potential circular imports between models and platform packages.
- Simplifies future integration with platform components (SCS sessions, CSRF, DB).

No functional changes to configuration loading structure and JSON schema remain the same; only the package location and imports were updated.

internal/platform/config/types.go

@@ -0,0 +1,40 @@
+package config
+
+type Config struct {
+	CSRF struct {
+		CSRFKey string `json:"csrfKey"`
+	} `json:"csrf"`
+
+	Database struct {
+		Server                string `json:"server"`
+		Port                  int    `json:"port"`
+		DatabaseNamed         string `json:"databaseName"`
+		MaxOpenConnections    int    `json:"maxOpenConnections"`
+		MaxIdleConnections    int    `json:"maxIdleConnections"`
+		ConnectionMaxLifetime string `json:"connectionMaxLifetime"`
+		Username              string `json:"username"`
+		Password              string `json:"password"`
+	}
+
+	HttpServer struct {
+		Port           int    `json:"port"`
+		Address        string `json:"address"`
+		ProductionMode bool   `json:"productionMode"`
+	} `json:"httpServer"`
+
+	License struct {
+		APIURL string `json:"apiUrl"`
+		APIKey string `json:"apiKey"`
+	} `json:"license"`
+
+	Session struct {
+		AuthKeyPath       string `json:"authKeyPath"`
+		EncryptionKeyPath string `json:"encryptionKeyPath"`
+		Name              string `json:"name"`
+	} `json:"session"`
+
+	Site struct {
+		SiteName           string `json:"siteName"`
+		CopyrightYearStart int    `json:"copyrightYearStart"`
+	} `json:"site"`
+}