fix(ci): restore *vcsURL default in --gitea-url alias registration

flag.StringVar sets *p = value at registration time. Using "" as the
default overwrites the env-resolved value that --vcs-url already stored
in *vcsURL. Restore *vcsURL as the default to preserve the GITEA_URL /
VCS_URL / GITHUB_SERVER_URL resolution chain.

Fixes CI error: --vcs-url (or --gitea-url) is required for provider=gitea

cmd/review-bot/main.go

@@ -85,8 +85,9 @@ func main() {
 	aicoreResourceGroup := flag.String("aicore-resource-group", envOrDefault("AICORE_RESOURCE_GROUP", "default"), "SAP AI Core resource group (for provider=aicore)")
 
 	// Backward-compatible alias: --gitea-url shares vcsURL's pointer (last flag wins).
-	// Shares vcsURL pointer; empty default avoids ordering dependency with vcsURL declaration.
-	flag.StringVar(vcsURL, "gitea-url", "", "Deprecated: use --vcs-url instead")
+	// Must use *vcsURL as default: StringVar sets *p=value at registration, so empty
+	// string would overwrite the env-resolved value from the --vcs-url declaration.
+	flag.StringVar(vcsURL, "gitea-url", *vcsURL, "Deprecated: use --vcs-url instead")
 
 	flag.Parse()