Add Go module scaffold with dependencies and entrypoint

Initialize the publix-deals Go module (go 1.24.4) with core
dependencies: cobra for CLI structure, lipgloss for styled terminal
output, testify for assertions, and x/term for TTY detection.

The main entrypoint at cmd/pubcli/main.go delegates to cmd.Execute().
The .gitignore covers Go build artifacts, editor files, coverage
output, and jj VCS state.

cmd/pubcli/main.go

@@ -0,0 +1,7 @@
+package main
+
+import "github.com/tayloree/publix-deals/cmd"
+
+func main() {
+	cmd.Execute()
+}