gh agent-task view: accept /agent-sessions/* URL as argument

[babakks]

This PR adds support for PR agent-session URLs, in the form of:

https://github.com/OWNER/REPO/pull/NUMBER/agent-sessions/SESSION-ID

A/C verification

When I run gh agent-task view https://github.com/OWNER/REPO/pull/NUMBER/agent-sessions/SESSION-ID
Then I see the details of the session identified by SESSION-ID

Confirmed:

[Copilot]

Pull Request Overview

This PR adds support for accepting PR agent-session URLs in the gh agent-task view command, allowing users to pass URLs like https://github.com/OWNER/REPO/pull/NUMBER/agent-sessions/SESSION-ID as arguments to directly view specific agent sessions.

• Extends the existing URL parsing functionality in PR commands to handle additional path segments after the pull request number
• Adds new agent-task functionality including create, list, and view commands for GitHub Copilot agent tasks
• Implements URL parsing for PR agent-session URLs to extract session IDs

Reviewed Changes

Copilot reviewed 12 out of 12 changed files in this pull request and generated 3 comments.

Show a summary per file

File	Description
pkg/cmd/root/root.go	Adds agent-task command registration to the CLI root
pkg/cmd/pr/shared/finder.go	Extends ParseURL to return additional path segments and adds ParseFullReference function
pkg/cmd/pr/shared/finder_test.go	Adds comprehensive tests for URL parsing with additional path segments
pkg/cmd/pr/edit/edit.go	Updates ParseURL call to handle new return signature
Multiple agent-task files	Implements complete agent-task command suite with create, list, and view functionality
api/queries_*.go	Adds Repository field to PullRequest and DatabaseID to GitHubUser structs
go.mod	Adds msgpack dependency for GraphQL node ID encoding

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[BagToad]

Looks good! Left some comments but it's really mostly about naming stuff so take it or leave it 👍 🍻