feat: Sprint 0 — GoFiber + HTMX + TailwindCSS v4 scaffolding

- Go module: git.tukangketik.id/swanadiva/hostkeeper/v2
- GoFiber v2 server with static, template engine, middleware
- HTMX + Alpine.js (downloaded from CDN)
- TailwindCSS v4 with custom theme (Lumina System colors)
- Custom CSS: dot-grid, glassmorphism, animations, toggle, modal
- Layout template (sidebar nav + header + main)
- Dashboard page with host list, search, filter, view toggle
- Health endpoint: GET /api/health

app/backend/internal/handler/health.go

@@ -0,0 +1,10 @@
+package handler
+
+import "github.com/gofiber/fiber/v2"
+
+func Health(c *fiber.Ctx) error {
+	return c.JSON(fiber.Map{
+		"status": "ok",
+		"app":    "hostkeeper-v2",
+	})
+}