feat: rewrite gh-commit in Go with local Ollama backend

Replaces the Python/Crush/DuckDB implementation with a CGO-free Go binary:
cobra CLI, modernc.org/sqlite storage, huh/lipgloss UI, and speed-tuned raw
/api/generate calls (think:false, keep_alive, capped num_predict) against a
local qwen3.5:2b. Ships as a gh extension via cli/gh-extension-precompile.

cmd/sync.go

@@ -0,0 +1,76 @@
+package cmd
+
+import (
+	"crypto/md5" //nolint:gosec // non-cryptographic: stable label color derivation
+	"encoding/hex"
+	"fmt"
+	"os/exec"
+	"strings"
+
+	"github.com/spf13/cobra"
+
+	"github.com/prdlk/gh-commit/internal/ui"
+)
+
+var syncCmd = &cobra.Command{
+	Use:   "sync",
+	Short: "Sync scopes to GitHub labels",
+	Args:  cobra.NoArgs,
+	RunE: func(_ *cobra.Command, _ []string) error {
+		repoPath, err := requireGit()
+		if err != nil {
+			return err
+		}
+
+		hasScopes, err := store.HasScopes(repoPath)
+		if err != nil {
+			return err
+		}
+		if !hasScopes {
+			ui.Errorf("Repository not configured — run 'gh commit init' first")
+			return errAborted
+		}
+
+		if _, err := exec.LookPath("gh"); err != nil {
+			ui.Errorf("Error: 'gh' command not found")
+			return errAborted
+		}
+		if exec.Command("gh", "repo", "view").Run() != nil {
+			ui.Errorf("Error: Not a GitHub repository or not authenticated")
+			return errAborted
+		}
+
+		ui.MagentaBoldf("Syncing scopes → GitHub labels...")
+		ui.Println()
+		scopes, err := store.Scopes(repoPath)
+		if err != nil {
+			return err
+		}
+
+		created, updated, failed := 0, 0, 0
+		for _, name := range sortedScopeNames(scopes) {
+			desc := "Changes to: " + strings.Join(scopes[name], ", ")
+			sum := md5.Sum([]byte(name)) //nolint:gosec // see import note
+			color := hex.EncodeToString(sum[:])[:6]
+
+			if exec.Command("gh", "label", "create", name, "--description", desc, "--color", color).Run() == nil {
+				ui.Printf("  %s Created: %s", ui.Green("✓"), name)
+				created++
+			} else if exec.Command("gh", "label", "edit", name, "--description", desc, "--color", color).Run() == nil {
+				ui.Printf("  %s Updated: %s", ui.Yellow("↻"), name)
+				updated++
+			} else {
+				ui.Printf("  %s Failed: %s", ui.Red("✗"), name)
+				failed++
+			}
+		}
+
+		ui.Println()
+		ui.SuccessBoldf("Sync complete! %s", fmt.Sprintf("Created: %d | Updated: %d | Failed: %d", created, updated, failed))
+		return nil
+	},
+}
+
+func init() {
+	rootCmd.AddCommand(syncCmd)
+}