fix: add conan export to Dockerfile and README build steps

The vendored corrade/cci.20260327 recipe must be exported before any
conan install/cmake invocation on a clean cache. Update:
- docker/Dockerfile: COPY conan/ and run conan export before cmake
- README.md: add conan export step to the local build instructions

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

Author: leoparente

README.md

@@ -606,6 +606,8 @@ The general build steps are:
 git clone https://github.com/netboxlabs/pktvisor.git
 cd pktvisor/
 conan profile detect -f
+# export the vendored Corrade recipe (not in conan-center)
+conan export conan/corrade/ --name=corrade --version=cci.20260327
 cd build/
 # configure and handle dependencies 
 cmake -DCMAKE_BUILD_TYPE=Release -DCMAKE_PROJECT_TOP_LEVEL_INCLUDES=./cmake/conan_provider.cmake ..

docker/Dockerfile

@@ -21,11 +21,13 @@ COPY ./cmake/ /pktvisor-src/cmake/
 COPY ./CMakeLists.txt /pktvisor-src/
 COPY ./conanfile.py /pktvisor-src/
 COPY ./.conanrc /pktvisor-src/
+COPY ./conan/ /pktvisor-src/conan/
 
 WORKDIR /pktvisor-src
 
 RUN \
     conan profile detect -f && \
+    conan export conan/corrade/ --name=corrade --version=cci.20260327 && \
     cd build/ && \
     PKG_CONFIG_PATH=/local/lib/pkgconfig cmake -DCMAKE_BUILD_TYPE=Release -DCMAKE_PROJECT_TOP_LEVEL_INCLUDES=./cmake/conan_provider.cmake .. && \
     make all -j 4