[FEATURE] [0.0.4-alpha] Add PR List Command

[codvy8282]

Project

cortex-cli

Description

There's no command to list pull requests in the current repository. Users must switch to git or GitHub CLI for this functionality.

Use Case

$ cortex pr list
error: unrecognized subcommand 'list'

Proposed Solution

1. Add cortex pr list command
2. Show open PRs by default
3. Filter options: --state, --author, --label
4. Sort options: --sort created|updated

Alternatives Considered

No response

Impact

All users

Additional Context

1. Common workflow need
2. Stay in Cortex context
3. Complement existing PR commands

[echobt]

Fixed in PR CortexLM/cortex-cli#409 [skip ci]