ci: add automated conflict detection bot for PRs

Author: Kingsman-99

.github/workflows/conflict-check.yml

@@ -0,0 +1,54 @@
+name: Conflict Check
+
+on:
+  pull_request:
+    branches: [main]
+    types: [opened, synchronize, reopened]
+
+jobs:
+  check-conflicts:
+    runs-on: ubuntu-latest
+    permissions:
+      pull-requests: write
+    steps:
+      - name: Check for merge conflicts
+        uses: actions/github-script@v7
+        with:
+          script: |
+            let mergeable = null;
+            let attempts = 0;
+
+            // Poll until GitHub computes mergeability (can take a few seconds)
+            while (mergeable === null && attempts < 10) {
+              await new Promise(r => setTimeout(r, 3000));
+              const { data: pr } = await github.rest.pulls.get({
+                owner: context.repo.owner,
+                repo: context.repo.repo,
+                pull_number: context.issue.number,
+              });
+              mergeable = pr.mergeable;
+              attempts++;
+            }
+
+            if (mergeable === false) {
+              // Avoid posting duplicate comments
+              const { data: comments } = await github.rest.issues.listComments({
+                owner: context.repo.owner,
+                repo: context.repo.repo,
+                issue_number: context.issue.number,
+              });
+
+              const alreadyCommented = comments.some(c =>
+                c.body.includes('Merge Conflict Detected') &&
+                c.user.login === 'github-actions[bot]'
+              );
+
+              if (!alreadyCommented) {
+                await github.rest.issues.createComment({
+                  owner: context.repo.owner,
+                  repo: context.repo.repo,
+                  issue_number: context.issue.number,
+                  body: `⚠️ **Merge Conflict Detected**\n\nThis PR has conflicts with \`main\` that must be resolved before it can be merged.\n\n**Steps to fix:**\n\`\`\`bash\ngit checkout main\ngit pull origin main\ngit checkout your-branch\ngit merge main\n# resolve conflicts in your editor\ngit add .\ngit commit\ngit push\n\`\`\`\n\nIf you need help resolving the conflict, leave a comment and the maintainer will assist.\n\n---\n*🤖 Automated conflict check*`
+                });
+              }
+            }