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)

tests/test_glob.c

@@ -0,0 +1,63 @@
+#include "test_glob.h"
+#include "utils.h"
+#include "test_utils.h"
+#include <string.h>
+
+static void test_glob_exact_match() {
+  EXPECT_TRUE(glob_match("foo", "foo"));
+}
+
+static void test_glob_question_mark() {
+  EXPECT_TRUE(glob_match("f?o", "foo"));
+  EXPECT_FALSE(glob_match("f?o", "fo"));
+}
+
+static void test_glob_star() {
+  EXPECT_TRUE(glob_match("*.txt", "foo.txt"));
+  EXPECT_TRUE(glob_match("*.txt", "a.txt"));
+}
+
+static void test_glob_star_mid() {
+  EXPECT_TRUE(glob_match("f*o", "foo"));
+  EXPECT_TRUE(glob_match("f*o", "fxxo"));
+  EXPECT_FALSE(glob_match("f*o", "bar"));
+}
+
+static void test_glob_no_match() {
+  EXPECT_FALSE(glob_match("foo", "bar"));
+}
+
+static void test_glob_empty_pattern() {
+  EXPECT_TRUE(glob_match("", ""));
+  EXPECT_FALSE(glob_match("", "foo"));
+}
+
+static void test_glob_star_all() {
+  EXPECT_TRUE(glob_match("*", "anything"));
+}
+
+static void test_glob_slash_not_matched() {
+  EXPECT_FALSE(glob_match("f*o", "f/o"));
+}
+
+static void test_glob_complex() {
+  EXPECT_TRUE(glob_match("*.c", "main.c"));
+  EXPECT_FALSE(glob_match("*.c", "main.h"));
+}
+
+static void test_glob_question_star() {
+  EXPECT_TRUE(glob_match("?*.txt", "a.txt"));
+}
+
+void test_glob() {
+  test_glob_exact_match();
+  test_glob_question_mark();
+  test_glob_star();
+  test_glob_star_mid();
+  test_glob_no_match();
+  test_glob_empty_pattern();
+  test_glob_star_all();
+  test_glob_slash_not_matched();
+  test_glob_complex();
+  test_glob_question_star();
+}