New approval/call statuses for stalled uploads

Two new call outcome states, write_unresolved and approval_write_unresolved, now surface when a stalled connection prevents a tool call from being confirmed as sent. The user-facing message explains that the session's connection to the service was backed up, with the upload either not completing or ending without an answer. A parallel message covers the matching case for approvals: the tool itself may not have received the approval because the session's upload of that approval could not be confirmed in time.