feat(vcs): complete Phase 1 — util.go, type cleanup, interface additions (fixes #84, #85, #86)

- Create vcs/util.go with GetAllFilesInPath and BuildLineToPositionMap
- Create vcs/util_test.go with comprehensive tests for both functions
- Remove review.ContentEntry type, replace with vcs.ContentEntry
- Remove review.GiteaClient interface, replace with vcs.FileReader
- Update review/repo_persona.go to use vcs.FileReader
- Update review/repo_persona_test.go to use vcs.ContentEntry
- Update cmd/review-bot/main.go adapter to implement vcs.FileReader
- Add Number and Base fields to vcs.PullRequest
- Add CommitStatus type to vcs/types.go
- Add GetFileContentAtRef to vcs.PRReader interface
- Add GetCommitStatuses to vcs.PRReader interface
- Add DismissReview to vcs.Reviewer interface
- Add stub implementations on gitea.Client for new interface methods

Closes #84, Closes #85, Closes #86

vcs/interfaces.go

@@ -10,6 +10,8 @@ type PRReader interface {
 	GetPullRequest(ctx context.Context, owner, repo string, number int) (*PullRequest, error)
 	GetPullRequestDiff(ctx context.Context, owner, repo string, number int) (string, error)
 	GetPullRequestFiles(ctx context.Context, owner, repo string, number int) ([]ChangedFile, error)
+	GetFileContentAtRef(ctx context.Context, owner, repo, path, ref string) (string, error)
+	GetCommitStatuses(ctx context.Context, owner, repo, sha string) ([]CommitStatus, error)
 }
 
 // FileReader can fetch file contents and list directory entries.
@@ -23,6 +25,7 @@ type Reviewer interface {
 	PostReview(ctx context.Context, owner, repo string, number int, req ReviewRequest) (*Review, error)
 	ListReviews(ctx context.Context, owner, repo string, number int) ([]Review, error)
 	DeleteReview(ctx context.Context, owner, repo string, number int, reviewID int64) error
+	DismissReview(ctx context.Context, owner, repo string, number int, reviewID int64, message string) error
 }
 
 // Identity can report who the authenticated user is.