Live transcription for Basic Support agents

Added a live call transcript drawer in the assistant while a call is active, including expand and resize, per-message and full-transcript copy, speaker grouping, and streaming updates (on Policies and AI Chat).

Added in-page transcript search with match highlighting in both the live transcription view and the conversation transcript view.

Added public API support to update a conversation with PATCH and to fetch a single platform user with GET, including assignee group context where applicable. *Available to select pilot partners

Fixed the assistant side panel closing on its own shortly after opening from a link; it now stays open until you dismiss it.

Fixed outbound email failures on very long threads by limiting the References header size while keeping correct threading.

Fixed handling of empty AssemblyAI transcript payloads so transcript finalization no longer errors unexpectedly.

Fixed conversation submission when email addresses differ only by letter casing so the correct channel is selected for the first message.