feat(server): initialize project skeleton with db and api setup

Establish the foundational structure for the ez-api server.

Key changes include:
- Set up main entry point with graceful shutdown and Gin router
- Configure database connections for PostgreSQL (GORM) and Redis
- Define core data models (User, Provider, Key, Model)
- Implement configuration loading and basic key creation handler
- Add Dockerfile for multi-stage builds and .gitignore

internal/config/config.go

@@ -0,0 +1,58 @@
+package config
+
+import (
+	"os"
+	"strconv"
+)
+
+type Config struct {
+	Server   ServerConfig
+	Postgres PostgresConfig
+	Redis    RedisConfig
+}
+
+type ServerConfig struct {
+	Port string
+}
+
+type PostgresConfig struct {
+	DSN string
+}
+
+type RedisConfig struct {
+	Addr     string
+	Password string
+	DB       int
+}
+
+func Load() (*Config, error) {
+	return &Config{
+		Server: ServerConfig{
+			Port: getEnv("EZ_API_PORT", "8080"),
+		},
+		Postgres: PostgresConfig{
+			DSN: getEnv("EZ_PG_DSN", "host=localhost user=postgres password=postgres dbname=ezapi port=5432 sslmode=disable"),
+		},
+		Redis: RedisConfig{
+			Addr:     getEnv("EZ_REDIS_ADDR", "localhost:6379"),
+			Password: getEnv("EZ_REDIS_PASSWORD", ""),
+			DB:       getEnvInt("EZ_REDIS_DB", 0),
+		},
+	}, nil
+}
+
+func getEnv(key, fallback string) string {
+	if value, ok := os.LookupEnv(key); ok {
+		return value
+	}
+	return fallback
+}
+
+func getEnvInt(key string, fallback int) int {
+	if value, ok := os.LookupEnv(key); ok {
+		if i, err := strconv.Atoi(value); err == nil {
+			return i
+		}
+	}
+	return fallback
+}