docs: improve CLI help, shell completion, and README

- Add command groups (Getting Started, Search, Downloads, Daemon, System)
- Add shell completion command (bash, zsh, fish, powershell)
- Add flag completions for --type, --quality, --sort, --lang, --genre,
  --country, --method, --player
- Improve Long descriptions and Examples for all commands
- Split doctor disk check into platform-specific files (Unix/Windows)
- Validate infoHash length before truncating (prevent panic)
- Fix references to non-existent 'unarr daemon start' command
- Move stats command to System & Diagnostics group
- Rewrite README with complete documentation, correct config format
  (toml not yaml), all commands, shell completion section

internal/cmd/self_update.go

@@ -0,0 +1,125 @@
+package cmd
+
+import (
+	"context"
+	"fmt"
+	"os"
+	"os/exec"
+	"runtime"
+	"strings"
+	"syscall"
+
+	"github.com/fatih/color"
+	"github.com/spf13/cobra"
+	"github.com/torrentclaw/torrentclaw-cli/internal/upgrade"
+)
+
+func newSelfUpdateCmd() *cobra.Command {
+	var force bool
+
+	cmd := &cobra.Command{
+		Use:   "self-update",
+		Short: "Update unarr to the latest version",
+		Long: `Download and install the latest version of unarr.
+
+Checks GitHub for the latest release, verifies the checksum, and
+replaces the current binary. A backup is kept at <binary>.backup.`,
+		Example: `  unarr self-update
+  unarr self-update --force`,
+		RunE: func(cmd *cobra.Command, args []string) error {
+			return runSelfUpdate(force)
+		},
+	}
+
+	cmd.Flags().BoolVarP(&force, "force", "f", false, "reinstall even if already up to date")
+
+	return cmd
+}
+
+func runSelfUpdate(force bool) error {
+	bold := color.New(color.Bold)
+	green := color.New(color.FgGreen)
+	yellow := color.New(color.FgYellow)
+
+	fmt.Println()
+	bold.Println("  unarr self-update")
+	fmt.Println()
+
+	// Check latest version
+	fmt.Print("  Checking latest version... ")
+	ctx := context.Background()
+	latest, err := upgrade.CheckLatest(ctx)
+	if err != nil {
+		fmt.Println()
+		return fmt.Errorf("could not check latest version: %w", err)
+	}
+
+	currentClean := strings.TrimPrefix(Version, "v")
+	fmt.Printf("v%s\n", latest)
+	fmt.Printf("  Current version: v%s\n", currentClean)
+
+	if currentClean == latest && !force {
+		fmt.Println()
+		green.Println("  ✓ Already up to date!")
+		fmt.Println()
+		return nil
+	}
+
+	if currentClean == latest && force {
+		yellow.Println("  Forcing reinstall...")
+	}
+
+	fmt.Println()
+
+	upgrader := &upgrade.Upgrader{
+		CurrentVersion: currentClean,
+		OnProgress: func(msg string) {
+			fmt.Printf("  %s\n", msg)
+		},
+	}
+
+	result := upgrader.Execute(ctx, latest)
+
+	fmt.Println()
+	if !result.Success {
+		return fmt.Errorf("upgrade failed: %v", result.Error)
+	}
+
+	green.Printf("  ✓ Upgraded v%s → v%s\n", result.OldVersion, result.NewVersion)
+	if result.BackupPath != "" {
+		fmt.Printf("  Backup: %s\n", result.BackupPath)
+	}
+	fmt.Println()
+
+	// If running as daemon, re-exec to restart with new binary
+	// For interactive use, just suggest restarting
+	if isRunningAsDaemon() {
+		fmt.Println("  Restarting daemon with new version...")
+		binPath, err := os.Executable()
+		if err != nil {
+			return fmt.Errorf("could not determine executable path: %w", err)
+		}
+		execErr := syscall.Exec(binPath, os.Args, os.Environ())
+		if execErr != nil && runtime.GOOS == "windows" {
+			// Windows doesn't support syscall.Exec — start new process
+			proc := exec.Command(binPath, os.Args[1:]...)
+			proc.Stdout = os.Stdout
+			proc.Stderr = os.Stderr
+			proc.Stdin = os.Stdin
+			return proc.Start()
+		}
+		return execErr
+	}
+
+	return nil
+}
+
+func isRunningAsDaemon() bool {
+	// Simple heuristic: check if "start" was in the original args
+	for _, arg := range os.Args {
+		if arg == "start" {
+			return true
+		}
+	}
+	return false
+}