fix: recover from unrelated histories on git pull

When the remote history has diverged (e.g. force-push), fall back to
git fetch + reset --hard origin/HEAD instead of failing with exit 128.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Author: CTOUT

scripts/sync-awesome-copilot.ps1

@@ -150,8 +150,18 @@ if ($IsFirstRun) {
     # Re-apply sparse-checkout in case -Categories changed since last run
     & git -C $Dest sparse-checkout set @CategoriesList 2>&1 | Out-Null
 
-    & git -C $Dest pull 2>&1 | ForEach-Object { Write-Log $_ }
-    if ($LASTEXITCODE -and $LASTEXITCODE -ne 0) { Write-Log "Pull failed (exit $LASTEXITCODE)" 'ERROR'; exit $LASTEXITCODE }
+    $pullOutput = & git -C $Dest pull 2>&1
+    $pullOutput | ForEach-Object { Write-Log $_ }
+    if ($LASTEXITCODE -and $LASTEXITCODE -ne 0) {
+        if (($pullOutput -join "`n") -match 'unrelated histories') {
+            Write-Log "Unrelated histories detected — fetching and resetting to remote HEAD..." 'WARN'
+            & git -C $Dest fetch origin 2>&1 | ForEach-Object { Write-Log $_ }
+            & git -C $Dest reset --hard origin/HEAD 2>&1 | ForEach-Object { Write-Log $_ }
+            if ($LASTEXITCODE -and $LASTEXITCODE -ne 0) { Write-Log "Reset failed (exit $LASTEXITCODE)" 'ERROR'; exit $LASTEXITCODE }
+        } else {
+            Write-Log "Pull failed (exit $LASTEXITCODE)" 'ERROR'; exit $LASTEXITCODE
+        }
+    }
 }
 
 Check-Timeout