Add HTTP layer and server setup

- Add strict configuration management (no fallbacks)
- Create HTTP router with Chi and CORS middleware
- Implement health check endpoint
- Add main entry point with database initialization
- Server runs on configurable host and port

cmd/api/main.go

@@ -0,0 +1,33 @@
+package main
+
+import (
+	"fmt"
+	"log"
+	"net/http"
+
+	"habit-tracker-api/internal/infrastructure/config"
+	httpInfra "habit-tracker-api/internal/infrastructure/http"
+	"habit-tracker-api/internal/infrastructure/persistence/sqlite"
+)
+
+func main() {
+	cfg, err := config.Load()
+	if err != nil {
+		log.Fatalf("Failed to load config: %v", err)
+	}
+
+	db, err := sqlite.NewDatabase(cfg.DBPath)
+	if err != nil {
+		log.Fatalf("Failed to connect to database: %v", err)
+	}
+	defer db.Close()
+
+	router := httpInfra.NewRouter(cfg.CORSOrigins)
+
+	addr := fmt.Sprintf("%s:%s", cfg.Host, cfg.Port)
+	log.Printf("Server starting on %s", addr)
+
+	if err := http.ListenAndServe(addr, router); err != nil {
+		log.Fatalf("Server failed: %v", err)
+	}
+}