refactor: consolidate tests/ to test/ directory

Consolidates duplicate test directories into Mason-standard `test/` (singular).

**Changes:**
- Move `tests/unit/` → `test/unit/`
- Move `tests/properties/` → `test/properties/`
- Remove empty `tests/` directory
- Update all CI references: `tests/` → `test/` in both GitHub Actions and GitLab CI

**Structure:**
```
test/
├── BasicTests.chpl       # Basic smoke tests
├── unit/                 # Unit tests
│   ├── GeneratorTests.chpl
│   ├── PropertyTests.chpl
│   └── ShrinkerTests.chpl
└── properties/           # Property-based tests
    └── SelfTests.chpl
```

All tests verified passing after consolidation.

Author: OutBot CI

.github/workflows/ci.yml

@@ -47,19 +47,19 @@ jobs:
       - name: Run Generator Tests
         run: |
           echo "Running Generator Tests..."
-          chpl tests/unit/GeneratorTests.chpl src/*.chpl -o /tmp/generator_tests
+          chpl test/unit/GeneratorTests.chpl src/*.chpl -o /tmp/generator_tests
           /tmp/generator_tests
 
       - name: Run Shrinker Tests
         run: |
           echo "Running Shrinker Tests..."
-          chpl tests/unit/ShrinkerTests.chpl src/*.chpl -o /tmp/shrinker_tests
+          chpl test/unit/ShrinkerTests.chpl src/*.chpl -o /tmp/shrinker_tests
           /tmp/shrinker_tests
 
       - name: Run Property Tests
         run: |
           echo "Running Property Tests..."
-          chpl tests/unit/PropertyTests.chpl src/*.chpl -o /tmp/property_tests
+          chpl test/unit/PropertyTests.chpl src/*.chpl -o /tmp/property_tests
           /tmp/property_tests
 
   test-examples:
@@ -104,7 +104,7 @@ jobs:
 
       - name: Run quickchpl self-tests
         run: |
-          chpl tests/properties/SelfTests.chpl src/*.chpl -o /tmp/self_tests
+          chpl test/properties/SelfTests.chpl src/*.chpl -o /tmp/self_tests
           /tmp/self_tests --numTests=${{ env.QUICKCHPL_NUM_TESTS }}
 
   test-matrix:
@@ -124,7 +124,7 @@ jobs:
       - name: Build with Chapel ${{ matrix.chapel-version }}
         run: |
           chpl --version
-          chpl tests/unit/GeneratorTests.chpl src/*.chpl -o /tmp/test
+          chpl test/unit/GeneratorTests.chpl src/*.chpl -o /tmp/test
           /tmp/test
 
   lint:

.gitlab-ci.yml

@@ -97,21 +97,21 @@ test:unit:generators:
   stage: test
   script:
     - echo "Running Generator Tests..."
-    - chpl tests/unit/GeneratorTests.chpl src/*.chpl -o /tmp/generator_tests
+    - chpl test/unit/GeneratorTests.chpl src/*.chpl -o /tmp/generator_tests
     - /tmp/generator_tests
 
 test:unit:shrinkers:
   stage: test
   script:
     - echo "Running Shrinker Tests..."
-    - chpl tests/unit/ShrinkerTests.chpl src/*.chpl -o /tmp/shrinker_tests
+    - chpl test/unit/ShrinkerTests.chpl src/*.chpl -o /tmp/shrinker_tests
     - /tmp/shrinker_tests
 
 test:unit:properties:
   stage: test
   script:
     - echo "Running Property Tests..."
-    - chpl tests/unit/PropertyTests.chpl src/*.chpl -o /tmp/property_tests
+    - chpl test/unit/PropertyTests.chpl src/*.chpl -o /tmp/property_tests
     - /tmp/property_tests
 
 test:examples:
@@ -131,15 +131,15 @@ test:self:
   stage: test
   script:
     - echo "Running quickchpl self-tests..."
-    - chpl tests/properties/SelfTests.chpl src/*.chpl -o /tmp/self_tests
+    - chpl test/properties/SelfTests.chpl src/*.chpl -o /tmp/self_tests
     - /tmp/self_tests --numTests=$QUICKCHPL_NUM_TESTS
 
 # Matrix testing for Chapel versions
 .test:matrix:
   stage: test
   script:
     - chpl --version
-    - chpl tests/unit/GeneratorTests.chpl src/*.chpl -o /tmp/test
+    - chpl test/unit/GeneratorTests.chpl src/*.chpl -o /tmp/test
     - /tmp/test
 
 test:chapel-2.6.0: