Moves CAPI client initialization to a deferred function in ListOptions, simplifying command setup and improving testability. Updates tests to use the new client initialization pattern and adds more comprehensive test cases for session listing.
Simplifies logic for filtering sessions to only include those with valid pull request and repository data. This reduces nested conditionals and improves code readability.
Introduces a new 'list' subcommand under agent-task for listing agent tasks. Implements a Copilot API client for fetching agent sessions and hydrating them with pull request data. Updates PullRequest and PRRepository types to support new fields. Adds dependencies for msgpack and tagparser.
Co-Authored-By: Babak K. Shandiz <babakks@github.com>
