fix: use per-review comment fetching for Forgejo compatibility

Forgejo doesn't have the flat GET /pulls/{number}/comments endpoint
(returns 404). Replace pulls.listReviewComments() with a 2-phase
approach: fetch reviews first, then pulls.listCommentsForReview()
per-review in parallel. Updates tests to mock the new per-review API.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

src/forgejo/data/fetcher.ts

@@ -210,14 +210,16 @@ export async function fetchForgejoData({
   let rawReviews: GitHubReview[] = [];
 
   if (isPR) {
-    // Fetch PR details, files, commits, comments, reviews, and inline comments in parallel
+    // Phase 1: Fetch PR details, files, commits, comments, and reviews in parallel.
+    // Note: Forgejo doesn't have a flat /pulls/{number}/comments endpoint for
+    // review comments (returns 404). Instead, fetch review comments per-review
+    // in phase 2 after we have the review IDs.
     const [
       prResponse,
       filesResponse,
       commitsResponse,
       commentsResponse,
       reviewsResponse,
-      reviewCommentsResponse,
     ] = await Promise.all([
       octokits.rest.pulls.get({ owner, repo, pull_number: number }),
       octokits.rest.pulls.listFiles({
@@ -244,23 +246,35 @@ export async function fetchForgejoData({
         pull_number: number,
         per_page: 100,
       }),
-      octokits.rest.pulls.listReviewComments({
-        owner,
-        repo,
-        pull_number: number,
-        per_page: 100,
-      }),
     ]);
 
     const pr = prResponse.data;
     const files = filesResponse.data;
     const commits = commitsResponse.data;
 
+    // Phase 2: Fetch inline comments for each review in parallel.
+    // Forgejo uses GET /repos/{owner}/{repo}/pulls/{index}/reviews/{id}/comments
+    const reviewCommentArrays = await Promise.all(
+      reviewsResponse.data.map(async (review) => {
+        try {
+          const { data } = await octokits.rest.pulls.listCommentsForReview({
+            owner,
+            repo,
+            pull_number: number,
+            review_id: review.id,
+          });
+          return data;
+        } catch {
+          // Some reviews (e.g. pending) may not have accessible comments
+          return [];
+        }
+      }),
+    );
+    const allReviewCommentData = reviewCommentArrays.flat();
+
     // Map REST responses to internal types
     rawComments = mapRestComments(commentsResponse.data);
-    const mappedInlineComments = mapRestReviewComments(
-      reviewCommentsResponse.data,
-    );
+    const mappedInlineComments = mapRestReviewComments(allReviewCommentData);
     rawReviews = mapRestReviews(reviewsResponse.data, mappedInlineComments);
 
     // Map REST file objects to GitHubFile type