chore: reorganize test files into domain-specific subdirectories

- Moved unit tests for user authentication into `tests/unit/auth/`
- Relocated integration tests for payment processing to `tests/integration/payments/`
- Grouped API endpoint tests under `tests/api/` with separate files for each resource
- Updated test runner configuration to discover tests in new directory structure

test/number/comparison.wren

@@ -0,0 +1,18 @@
+io.write(1 < 2)    // expect: true
+io.write(2 < 2)    // expect: false
+io.write(2 < 1)    // expect: false
+
+io.write(1 <= 2)    // expect: true
+io.write(2 <= 2)    // expect: true
+io.write(2 <= 1)    // expect: false
+
+io.write(1 > 2)    // expect: false
+io.write(2 > 2)    // expect: false
+io.write(2 > 1)    // expect: true
+
+io.write(1 >= 2)    // expect: false
+io.write(2 >= 2)    // expect: true
+io.write(2 >= 1)    // expect: true
+
+// TODO(bob): Wrong type for RHS.
+// TODO(bob): Comparing zero and negative zero.