feat(prd-1): implement M7 - entry point + mode handler integration

- Tag mode routes to fetchForgejoData vs fetchGitHubData based on platform
- createInitialComment auto-detects platform for Forgejo spinner/URL format
- update-comment-link uses updateForgejoCommentBody + Forgejo PR compare URL
- update-with-branch uses platform-aware branch/job-run link formatting
- Agent mode needed NO changes (token in run.ts, rest uses Octokit REST)
- 11 new integration tests in test/m7-integration.test.ts
- 785 tests pass, typecheck clean, format clean

Progress: 78% complete (7/9 milestones) - M3, M8, M9 remaining

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

src/entrypoints/update-comment-link.ts

@@ -7,6 +7,11 @@ import {
   updateCommentBody,
   type CommentUpdateInput,
 } from "../github/operations/comment-logic";
+import {
+  updateForgejoCommentBody,
+  createForgejoPrCompareUrl,
+} from "../forgejo/comment-logic";
+import { detectPlatform } from "../platform/detector";
 import {
   parseGitHubContext,
   isPullRequestReviewCommentEvent,
@@ -46,6 +51,7 @@ export async function updateCommentLink(
   } = params;
 
   const { owner, repo } = context.repository;
+  const platform = detectPlatform();
 
   const serverUrl = GITHUB_SERVER_URL;
   const jobUrl = `${serverUrl}/${owner}/${repo}/actions/runs/${process.env.GITHUB_RUN_ID}`;
@@ -145,13 +151,26 @@ export async function updateCommentLink(
           (comparison.files && comparison.files.length > 0)
         ) {
           const entityType = context.isPR ? "PR" : "Issue";
-          const prTitle = encodeURIComponent(
-            `${entityType} #${context.entityNumber}: Changes from Claude`,
-          );
-          const prBody = encodeURIComponent(
-            `This PR addresses ${entityType.toLowerCase()} #${context.entityNumber}\n\nGenerated with [Claude Code](https://claude.ai/code)`,
-          );
-          const prUrl = `${serverUrl}/${owner}/${repo}/compare/${baseBranch}...${claudeBranch}?quick_pull=1&title=${prTitle}&body=${prBody}`;
+          const titleText = `${entityType} #${context.entityNumber}: Changes from Claude`;
+          const bodyText = `This PR addresses ${entityType.toLowerCase()} #${context.entityNumber}\n\nGenerated with [Claude Code](https://claude.ai/code)`;
+
+          let prUrl: string;
+          if (platform === "forgejo") {
+            // Forgejo doesn't support quick_pull=1
+            prUrl = createForgejoPrCompareUrl(
+              serverUrl,
+              owner,
+              repo,
+              baseBranch,
+              claudeBranch,
+              titleText,
+              bodyText,
+            );
+          } else {
+            const prTitle = encodeURIComponent(titleText);
+            const prBody = encodeURIComponent(bodyText);
+            prUrl = `${serverUrl}/${owner}/${repo}/compare/${baseBranch}...${claudeBranch}?quick_pull=1&title=${prTitle}&body=${prBody}`;
+          }
           prLink = `\n[Create a PR](${prUrl})`;
         }
       } catch (error) {
@@ -217,7 +236,10 @@ export async function updateCommentLink(
     errorDetails,
   };
 
-  const updatedBody = updateCommentBody(commentInput);
+  const updatedBody =
+    platform === "forgejo"
+      ? updateForgejoCommentBody(commentInput)
+      : updateCommentBody(commentInput);
 
   try {
     await updateClaudeComment(octokit.rest, {