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 and diff view.

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

Behavior:
- Only resolves after successful supersede (gated on supersedeOK)
- Aggregates failures and logs at warn level
- Truncates error bodies to 256 bytes (security)
- Non-fatal: review still posts even if resolution fails

cmd/review-bot/main.go

@@ -369,10 +369,39 @@ func main() {
 	if existingReview != nil && existingCommentID > 0 {
 		newReviewURL := fmt.Sprintf("%s/%s/%s/pulls/%d#pullrequestreview-%d", strings.TrimRight(*giteaURL, "/"), owner, repoName, prNumber, posted.ID)
 		supersededBody := buildSupersededBody(existingReview.Body, existingReview.CommitID, newReviewURL, sentinel)
+		supersedeOK := false
 		if err := giteaClient.EditComment(ctx, owner, repoName, existingCommentID, supersededBody); err != nil {
 			slog.Warn("could not mark old review as superseded", "comment_id", existingCommentID, "error", err)
 		} else {
 			slog.Info("marked old review as superseded", "old_state", existingReview.State, "new_review_id", posted.ID, "pr", prNumber)
+			supersedeOK = true
+		}
+
+		// Resolve old review's inline comments only after successful supersede
+		if supersedeOK {
+			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, failed := 0, 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)
+						failed++
+					} else {
+						resolved++
+					}
+				}
+				if resolved > 0 {
+					slog.Info("resolved old inline comments", "count", resolved, "pr", prNumber)
+				}
+				if failed > 0 {
+					slog.Warn("some inline comments could not be resolved", "failed", failed, "pr", prNumber)
+				}
+			}
 		}
 	}