feat: resolve old inline comments when superseding review

Closes #27

After superseding an old review, resolves all its inline comments via
POST /pulls/comments/{id}/resolve. This clears unresolved conversation
markers from the PR timeline/diff view.

New API methods:
- ListReviewComments: GET /repos/.../pulls/{n}/reviews/{id}/comments
- ResolveComment: POST /repos/.../pulls/comments/{id}/resolve

Failures are non-fatal (debug log) — the review still posts and
supersedes even if resolution fails.

cmd/review-bot/main.go

@@ -362,6 +362,27 @@ func main() {
 		} else {
 			slog.Info("marked old review as superseded", "old_state", existingReview.State, "new_review_id", posted.ID, "pr", prNumber)
 		}
+
+		// Resolve old review's inline comments (clears unresolved conversations in PR timeline)
+		oldComments, err := giteaClient.ListReviewComments(ctx, owner, repoName, prNumber, existingReview.ID)
+		if err != nil {
+			slog.Warn("could not list old review comments for resolution", "review_id", existingReview.ID, "error", err)
+		} else {
+			resolved := 0
+			for _, c := range oldComments {
+				if c.ID == 0 {
+					continue
+				}
+				if err := giteaClient.ResolveComment(ctx, owner, repoName, c.ID); err != nil {
+					slog.Debug("could not resolve inline comment", "comment_id", c.ID, "error", err)
+				} else {
+					resolved++
+				}
+			}
+			if resolved > 0 {
+				slog.Info("resolved old inline comments", "count", resolved, "pr", prNumber)
+			}
+		}
 	}
 
 }