fix(utils): prevent nil pointer panic in ResolvePartialID (#1132)

Add nil check at start of ResolvePartialID to return a proper error
instead of panicking when storage interface is nil.

Root cause: When bd refile (or other commands) is called with a nil
storage, calling store.SearchIssues() panics with SIGSEGV. This can
happen when routing fails to initialize storage properly.

Now returns: "cannot resolve issue ID <id>: storage is nil"

Fixes: bd-7ypor

Co-authored-by: Claude Opus 4.5 <noreply@anthropic.com>

internal/utils/id_parser_test.go

@@ -316,6 +316,21 @@ func TestResolvePartialID_NoConfig(t *testing.T) {
 	}
 }
 
+func TestResolvePartialID_NilStorage(t *testing.T) {
+	ctx := context.Background()
+
+	// Test that nil storage returns an error instead of panicking
+	_, err := ResolvePartialID(ctx, nil, "bd-123")
+	if err == nil {
+		t.Fatal("ResolvePartialID with nil storage should return error, got nil")
+	}
+
+	expectedMsg := "storage is nil"
+	if !contains(err.Error(), expectedMsg) {
+		t.Errorf("ResolvePartialID error = %q; want error containing %q", err.Error(), expectedMsg)
+	}
+}
+
 func TestExtractIssuePrefix(t *testing.T) {
 	tests := []struct {
 		name     string