fix(core): align ChatGPT token sharing with updated partner guide - #52162

Two fixes from the updated token-sharing guidance.

Error codes
The guide renamed the token-sharing error codes (dropped the v2_ prefix) and added two chatpass_v2_* codes. Our retry list and error messages still used the old names, and since matching is by substring, the new codes never matched — e.g. subscription_sharing_user_not_eligible was being retried and shown with the raw message.

• Rename the codes in nonRetryableSharingCodes and tokenSharingMessages
• Add chatpass_v2_scope_not_authorized and chatpass_v2_invalid_authorization_context (non-retryable, with a message)
• Drop subscription_sharing_v2_client_not_enabled, which the guide no longer lists

Client ID on reauthorization
The callback used result.clientID ?? savedID, so a reauthorization callback with a different client ID would silently switch the connection to another registration. The guide says to reject that. The saved client ID now wins, and a mismatch fails the attempt without saving a credential. New registrations still use the callback's client ID.

Tests

• Updated code tables in provider-chatgpt.test.ts and session-error.test.ts
• New test: a reauthorization callback with a different client_id fails and creates no credential