Normalize the default configuration discovery paths for all three config files, and update documentation and tests accordingly

internal/app/campaign_config_path_test.go

@@ -36,7 +36,7 @@ func TestResolveCampaignConfigPathUsesFirstExistingDefault(t *testing.T) {
 }
 
 func TestResolveCampaignConfigPathErrorIncludesSearchedPaths(t *testing.T) {
-	_, err := resolveCampaignConfigPathWithCandidates("", []string{"./campaign.yml", "/usr/local/etc/narratio/campaign.yml", "/etc/narratio/campaign.yml"})
+	_, err := resolveCampaignConfigPathWithCandidates("", []string{"/usr/local/etc/narratio/campaign.yml", "/etc/narratio/campaign.yml"})
 	if err == nil {
 		t.Fatal("expected error, got nil")
 	}