fix: treat empty string as "not set" for optional fields (#124)

Empty strings in default config (service, sshKeyPath, sshHost, gpgKeyId)
were causing validation errors on first install. This change skips
validation for empty strings while keeping required fields protected.

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Model-Raw: claude-opus-4-5-20251101

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

Author: nullvariant

extensions/git-id-switcher/src/configSchema.ts

@@ -129,7 +129,10 @@ function validateProperty(
   errors: SchemaError[]
 ): void {
   // Type check
-  if (value !== undefined && value !== null) {
+  // Empty string is treated as "not set" for optional fields.
+  // This allows default config with "" values to pass validation without errors.
+  // SECURITY: Required fields (id, name, email) are still protected via else-if below.
+  if (value !== undefined && value !== null && value !== '') {
     if (typeof value !== schema.type) {
       errors.push({
         field,