Support prolite plan type (#17419)

Addresses #17353

Problem: Codex rate-limit fetching failed when the backend returned the
new `prolite` subscription plan type.

Solution: Add `prolite` to the backend/account/auth plan mappings, keep
unknown WHAM plan values decodable, and regenerate app-server plan
schemas.

codex-rs/app-server-protocol/schema/json/ServerNotification.json

@@ -2010,6 +2010,7 @@
         "go",
         "plus",
         "pro",
+        "prolite",
         "team",
         "self_serve_business_usage_based",
         "business",