Refactor: thread-safe per-process state and add tests

Major changes:
- Move child state from global variable to server config (reqin_log_server_conf_t)
- Add reqin_log_create_server_conf() for proper per-server initialization
- Fix thread safety for worker/event MPMs
- Add cmocka unit tests (test_module_real.c)
- Add Python integration tests (test_integration.py)
- Update CI workflow and Dockerfiles for test execution
- Fix: Remove child_exit hook (not in architecture.yml)

Tests:
- Unit tests: JSON escaping, ISO8601 formatting, header truncation
- Integration tests: basic_logging, header_limits, socket_unavailable, socket_loss

Co-authored-by: Qwen-Coder <qwen-coder@alibabacloud.com>

Dockerfile.tests

@@ -14,6 +14,8 @@ RUN dnf install -y epel-release && \
     python3 \
     curl \
     git \
+    pkgconfig \
+    libxml2-devel \
     && dnf clean all
 
 # Build and install cmocka from source
@@ -22,13 +24,12 @@ RUN cd /tmp && \
     cd cmocka && \
     git checkout cmocka-1.1.5 && \
     mkdir build && cd build && \
-    cmake .. -DCMAKE_INSTALL_PREFIX=/usr && \
+    cmake .. -DCMAKE_INSTALL_PREFIX=/usr -DCMAKE_BUILD_TYPE=Release && \
     make && \
     make install && \
+    ldconfig && \
     cd / && \
-    rm -rf /tmp/cmocka && \
-    dnf remove -y git && \
-    dnf clean all
+    rm -rf /tmp/cmocka
 
 WORKDIR /build