ci: add libeigen3-dev to evaluator job to fix planning_node build

[Copilot]

The evaluator CI job was failing because libplanning_node.so was never built, causing the entire planning→control chain to be absent at runtime (0 Hz on planning/trajectory, control/raw_cmd, control/cmd; missing topology edges; collision detected).

Root cause

libeigen3-dev was missing from the CI install step. The dependency chain:

• CMakeLists.txt: find_package(Eigen3) fails → FLOWENGINE_HAVE_EIGEN=FALSE
• frenet_planner + frenet_bridge static libs are gated on FLOWENGINE_HAVE_EIGEN
• modules/adas_nodes/CMakeLists.txt: find_library(FRENET_BRIDGE ...) finds nothing → planning_node target silently disabled
• flow_launcher can't dlopen the planning plugin → no planning → no control → collision → all FAIL

Changes

• .github/workflows/ci.yml: Add libeigen3-dev to the evaluator and integration-test job install steps (both jobs build modules/adas_nodes plugins)

-run: sudo apt-get update -qq && sudo apt-get install -y -qq libcjson-dev python3
+run: sudo apt-get update -qq && sudo apt-get install -y -qq libcjson-dev python3 libeigen3-dev

• .gitignore: Add build_*/ pattern alongside existing build-*/ to cover underscore-named local build directories