Replace NotImplementedError stub with real implementation that fetches
a ticket by ID via CW REST API and maps it to PSATicket.
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
ConnectWiseProvider implements PSAProvider with test_connection() that
calls GET /system/info to verify credentials and connectivity. All other
methods raise NotImplementedError with slice references for future work.
Provider registry (get_provider_for_account) looks up the account's
PsaConnection, decrypts stored credentials, and instantiates the
correct provider. Currently supports connectwise only.
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
