Add git notes preservation system with backup/restore functionality

- Added WarnAboutGitNotesLoss hook that warns before destructive git operations
- Implemented comprehensive backup/restore system for conversation notes
- Added CLI commands: hooks notes backup/restore/list
- Configured git to automatically copy notes during rebase operations
- Created backup.go with full notes backup and restoration functionality

This ensures conversation context is never lost during rebasing, squashing, or other destructive git operations.

internal/handlers/gitrebase.go

@@ -0,0 +1,65 @@
+package handlers
+
+import (
+	"context"
+	"fmt"
+	"log/slog"
+	"strings"
+
+	"github.com/imjasonh/hooks/internal/hooks"
+)
+
+func init() {
+	hooks.RegisterHook(hooks.EventPreToolUse, "Bash", WarnAboutGitNotesLoss)
+}
+
+// WarnAboutGitNotesLoss warns users about potential git notes loss during destructive operations
+func WarnAboutGitNotesLoss(ctx context.Context, input hooks.HookInput) (hooks.HookOutput, error) {
+	bashInput, err := input.GetBashInput()
+	if err != nil {
+		return hooks.HookOutput{Decision: "approve"}, nil
+	}
+
+	command := strings.TrimSpace(bashInput.Command)
+
+	// Check for destructive git operations that might lose notes
+	destructiveOperations := []struct {
+		pattern string
+		warning string
+	}{
+		{
+			pattern: "git rebase",
+			warning: "⚠️  Git rebase can lose conversation notes attached to commits. Consider:\n" +
+				"   • Run 'git notes --ref=claude-conversations list' to see which commits have notes\n" +
+				"   • Use 'git -c notes.rewrite.mode=copy rebase' to preserve notes\n" +
+				"   • Or manually backup notes before rebasing with 'git notes --ref=claude-conversations show <commit>'",
+		},
+		{
+			pattern: "git reset --hard",
+			warning: "⚠️  Hard reset will lose commits and their conversation notes permanently.\n" +
+				"   • Consider using 'git reset --soft' or 'git reset --mixed' instead\n" +
+				"   • Backup important notes first with 'git notes --ref=claude-conversations show <commit>'",
+		},
+		{
+			pattern: "git commit --amend",
+			warning: "⚠️  Amending commits changes their hash and may lose conversation notes.\n" +
+				"   • Notes are attached to the original commit hash\n" +
+				"   • Consider creating a new commit instead of amending",
+		},
+	}
+
+	for _, op := range destructiveOperations {
+		if strings.Contains(command, op.pattern) {
+			slog.Info("warning user about potential git notes loss",
+				"command", command,
+				"operation", op.pattern)
+
+			return hooks.HookOutput{
+				Decision:          "approve", // Don't block, just warn
+				AdditionalContext: fmt.Sprintf("\n%s\n\nDo you want to proceed with this operation?", op.warning),
+			}, nil
+		}
+	}
+
+	return hooks.HookOutput{Decision: "approve"}, nil
+}