Initial project skeleton (M0)

Add SPECS.md, JSON config loader with env overrides and validation,
and an empty tview shell with tabs and status bar.

Co-Authored-By: Claude Sonnet 5.5 <noreply@anthropic.com>

cmd/arr-tui/main.go

@@ -0,0 +1,41 @@
+// Command arr-tui is a terminal UI for Radarr, Sonarr and SABnzbd.
+package main
+
+import (
+	"flag"
+	"fmt"
+	"os"
+
+	"git.stinnesbeck.com/nils/arr-tui/internal/config"
+	"git.stinnesbeck.com/nils/arr-tui/internal/ui"
+)
+
+func main() {
+	if err := run(); err != nil {
+		fmt.Fprintln(os.Stderr, "arr-tui:", err)
+		os.Exit(1)
+	}
+}
+
+func run() error {
+	path := flag.String("config", "", "path to config.json (default: $XDG_CONFIG_HOME/arr-tui/config.json)")
+	flag.Parse()
+
+	if *path == "" {
+		p, err := config.DefaultPath()
+		if err != nil {
+			return err
+		}
+		*path = p
+	}
+
+	_, warnings, err := config.Load(*path)
+	if err != nil {
+		return err
+	}
+	for _, w := range warnings {
+		fmt.Fprintln(os.Stderr, "warning:", w)
+	}
+
+	return ui.New().Run()
+}