fix: treat empty SOCKET_API_TOKEN as unset (#36)

When SOCKET_API_TOKEN is set to an empty string, the CLI should
fall back to the public proxy path (same as when the variable is
completely unset). Previously, `std::env::var().ok()` returned
`Some("")` for an empty-but-set variable, which passed the
`is_none()` check and sent the empty token to the authenticated
API endpoint, causing "Unauthorized" errors.

Co-authored-by: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: mikolalysenko

crates/socket-patch-core/src/api/client.rs

@@ -555,7 +555,9 @@ impl ApiClient {
 ///
 /// Returns `(client, use_public_proxy)`.
 pub async fn get_api_client_from_env(org_slug: Option<&str>) -> (ApiClient, bool) {
-    let api_token = std::env::var("SOCKET_API_TOKEN").ok();
+    let api_token = std::env::var("SOCKET_API_TOKEN")
+        .ok()
+        .filter(|t| !t.is_empty());
     let resolved_org_slug = org_slug
         .map(String::from)
         .or_else(|| std::env::var("SOCKET_ORG_SLUG").ok());