testing: add comprehensive test suite for test-driven development

Add unit tests for previously untested modules (protocol, data, metadata,
file, glob), robustness tests for deserialization of malformed inputs,
thread safety stress tests, property-based roundtrip tests, and 6 fuzz
targets. Update CI with CTest integration, coverage reporting, and
valgrind memory checking.

New test files:
- test_data.c: Data type lifecycle (5 tests)
- test_protocol.c: Protocol I/O roundtrips and error paths (9 tests)
- test_metadata.c: Metadata serialization roundtrips (6 tests)
- test_file.c: File operations and send/receive (12 tests)
- test_glob.c: Glob pattern matching (10 tests)
- test_robustness.c: Malformed input handling for chunk/delta/protocol (11 tests)
- test_stress.c: MPMC queue stress, backpressure, rapid create/destroy (3 tests)
- test_property.c: Compress, delta, chunk, glob roundtrip properties (4 tests)
- tests/fuzz/: 6 libFuzzer targets for deserialization functions

Extended existing tests:
- test_config.c: config_send/config_receive roundtrip via fork+pipe
- test_shared_utils.c: mkdir_r, glob_match, delete_extras

Infrastructure:
- CTest integration in CMakeLists.txt
- Coverage support (-DENABLE_COVERAGE=ON)
- Fuzz target support (-DENABLE_FUZZ=ON)
- CI: coverage, valgrind, address sanitizer jobs
- Fixed MPMC stress test race condition (cnd_signal -> cnd_broadcast)

.gitea/workflows/ci.yaml

@@ -31,10 +31,10 @@ jobs:
         run: cmake --build build -j$(nproc)
 
       - name: Unit Tests
-        run: ./build/tests
+        run: ctest --test-dir build --output-on-failure -j$(nproc)
 
       - name: Integration Tests
-        run: python3 -m pytest tests/ -v --tb=short
+        run: python3 -m pytest tests/integration/ -v --tb=short
 
   sanitizers:
     runs-on: ubuntu-latest
@@ -54,4 +54,44 @@ jobs:
         run: cmake --build build-${{ matrix.sanitizer }} -j$(nproc)
 
       - name: Unit Tests
-        run: ./build-${{ matrix.sanitizer }}/tests
+        run: ctest --test-dir build-${{ matrix.sanitizer }} --output-on-failure
+
+  coverage:
+    runs-on: ubuntu-latest
+    container: gitea.tap-tap.win/taptap/fastsync-ci:v7
+    needs: lint
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v4
+
+      - name: Configure
+        run: cmake -B build -S . -DENABLE_COVERAGE=ON -DSTRICT_WARNINGS=ON
+
+      - name: Build
+        run: cmake --build build -j$(nproc)
+
+      - name: Unit Tests
+        run: ctest --test-dir build --output-on-failure
+
+      - name: Coverage Report
+        run: |
+          lcov --capture --directory build --output-file coverage.info --rc lcov_branch_coverage=1
+          lcov --remove coverage.info '/usr/*' '*/tests/*' '*/xxhash/*' --output-file coverage.info
+          lcov --list coverage.info
+
+  valgrind:
+    runs-on: ubuntu-latest
+    container: gitea.tap-tap.win/taptap/fastsync-ci:v7
+    needs: lint
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v4
+
+      - name: Configure
+        run: cmake -B build -S . -DSTRICT_WARNINGS=ON
+
+      - name: Build
+        run: cmake --build build -j$(nproc)
+
+      - name: Valgrind Memcheck
+        run: valgrind --leak-check=full --show-leak-kinds=all --error-exitcode=1 ./build/tests