Add initial backend, CLI, and frontend scaffold

Bootstrap repository with multi-component scaffolding: a Spring Boot backend (Maven wrapper, pom.xml, BackendApplication, test, resources, .gitignore/.gitattributes), a Go CLI app using Cobra (root + subcommands: diff, log, login, pull, push, set, unset), prebuilt CLI binaries and a build script, and a Next.js frontend (configs, package.json, styles, pages, and static assets). This commit provides the skeleton for development across backend, CLI, and frontend components.

cli/main.go

@@ -0,0 +1,11 @@
+/*
+Copyright © 2026 NAME HERE <EMAIL ADDRESS>
+
+*/
+package main
+
+import "github.com/geneticglitch1/envsync-cli/cmd"
+
+func main() {
+	cmd.Execute()
+}