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/codex_app_server_protocol.schemas.json

@@ -9924,6 +9924,7 @@
           "go",
           "plus",
           "pro",
+          "prolite",
           "team",
           "self_serve_business_usage_based",
           "business",