bb pr list --author with @me support

[zoldyzdk]

Parent PRD

#1

What to build

Enhance the existing bb pr list command with an --author / -A flag that filters pull requests by author nickname. When the value @me is passed, resolve it to the authenticated user's nickname via GET /user.

End-to-end: the user runs bb pr list --author zoldyzdk or bb pr list --author @me and sees only PRs from that author. Running bb pr list without --author continues to show all PRs (preserving existing behavior).

This requires:

• Enhancing ListPullRequests in the API layer to accept a Bitbucket query string parameter (q=author.nickname="<value>")
• Adding the --author flag to the pr list Cobra command
• Resolving @me to the current user's nickname using the existing GetCurrentUser() API call

Acceptance criteria

• bb pr list --author <nickname> returns only PRs authored by that user
• bb pr list --author @me resolves to the authenticated user's nickname and filters accordingly
• bb pr list (without --author) continues to show all PRs (no behavior change)
• The --author flag works in combination with existing --state and --limit flags
• Clear error message if @me is used but the user is not authenticated

Blocked by

None - can start immediately

User stories addressed

• User story 21
• User story 22
• User story 23