[feat] add ci tests and workflow optimization

chore(ci,test,build): add CI/tests for GSIM, .sv and Java; xcomm fallback; test preflight
- CI: install default-jdk for Java tests
- Tests: add GSIM export smoke, .sv verilator build, Java export
- test/Makefile: add preflight to auto-clean + rebuild with python+java when missing
- Build: Makefile init falls back to latest master for xcomm when branch missing
- Wire new tests into default test targets
- Run build-and-test and appimage-build on all branches
- Restrict appimage-publish and docker-build-push to master
- Reuse build directory via artifact between jobs to avoid rebuilds
- Fix deps: install swig in CI and AppImage job
- Makefile appimage target reuses existing build/ for install & packing
- Remove standalone AppImage/docker workflows to prevent duplicate runs
- build-and-test: install base toolchain and Kitware CMake
- Build and install SWIG v4.2.1 from source
- Build and install Verilator v5.018 from source
- appimage-build: reuse build/ artifact; minimal deps (appimagetool, linuxdeploy)
- Keep: appimage-build on all branches; publish/docker only on master
- 在 test/Makefile 中让 smoke、sv_build、gsim_smoke 依赖 preflight
- 避免 preflight 执行 clean/rebuild 时其他并发目标找不到构建产物
- preflight 完成后仍保留测试阶段的并行度