test running / reporting improvements (#797)

**CI/CD improvements (validate.yml):**
- Add test reporter (`ue-foundation/test-reporter@v2`) for all three platforms, rendering JUnit test results directly in PR check runs
- Add "Trust workspace" step on Windows to fix git safe.directory ownership issue with self-hosted runners
- Clean stale report files before each test run to prevent false failures from leftover XML
- Broaden `paths-ignore` to skip builds for non-code changes (`*.md`, `LICENSE`, `.gitignore`, `docs/**`)

**Test improvements:**
- Convert `CHECK` to `REQUIRE` in several test suites (projectstore, integration, http) for fail-fast behavior
- Mark some tests with `doctest::skip()` for selective execution
- Skip httpclient transport tests pending investigation
- Add `--noskip` option to `xmake test` task
- Add `--repeat=<N>` option to `xmake test` task, to run tests repeatedly N times or until there is a failure

**xmake test output improvements:**
- Add totals row to test summary table
- Right-justify numeric columns in summary table

1 files changed, 2 insertions, 8 deletions

diff --git a/src/zenserver-test/cache-tests.cpp b/src/zenserver-test/cache-tests.cpp
index 0272d3797..745a89253 100644
--- a/src/zenserver-test/cache-tests.cpp
+++ b/src/zenserver-test/cache-tests.cpp
@@ -145,7 +145,7 @@ TEST_CASE("zcache.cbpackage")
 		for (const zen::CbAttachment& LhsAttachment : LhsAttachments)
 		{
 			const zen::CbAttachment* RhsAttachment = Rhs.FindAttachment(LhsAttachment.GetHash());
-			CHECK(RhsAttachment);
+			REQUIRE(RhsAttachment);
 
 			zen::SharedBuffer LhsBuffer = LhsAttachment.AsCompressedBinary().Decompress();
 			CHECK(!LhsBuffer.IsNull());
@@ -1373,14 +1373,8 @@ TEST_CASE("zcache.rpc")
 	}
 }
 
-TEST_CASE("zcache.failing.upstream")
+TEST_CASE("zcache.failing.upstream" * doctest::skip())
 {
-	// This is an exploratory test that takes a long time to run, so lets skip it by default
-	if (true)
-	{
-		return;
-	}
-
 	using namespace std::literals;
 	using namespace utils;