bee4d98b8c
- Add --provider flag (gitea|github) for VCS backend selection - Add --base-url flag for GitHub API endpoint configuration - Rename --gitea-url to --vcs-url with backward-compatible alias - Replace direct gitea.Client usage with vcs.Client interface - Create vcs.Client via factory switch based on --provider value - Implement Reviewer + Identity interfaces on github.Client - Add verdictToEvent() using canonical vcs.ReviewEvent types - Remove review.GiteaEvent() (replaced by verdictToEvent) - GitHub supersede uses DismissReview; Gitea keeps EditComment flow - Add VCS_PROVIDER, VCS_BASE_URL, VCS_URL env var support Closes #82