T0.1: Add test scripts and documentation

Add scripts/test.sh and scripts/test.bat to run go vet and go test -race.
Update docs/TESTS.md with test script usage and reorganized manual test commands.

Co-Authored-By: Claude Haiku 4.5 <noreply@anthropic.com>

scripts/test.sh

@@ -0,0 +1,16 @@
+#!/bin/bash
+
+# GoSentry test runner
+# Runs go vet and go test with race detection
+
+set -e
+
+echo "Running go vet..."
+go vet ./...
+
+echo ""
+echo "Running go test with race detection..."
+go test -race ./...
+
+echo ""
+echo "✓ All tests passed"