Add Ghidra ISF import/export scripts

[lacraig2]

Summary

• add bundled Ghidra scripts to export active programs to ISF and import ISF types/symbols/functions back into Ghidra
• document analyzeHeadless usage and package both scripts with dwarffi
• add focused parser/schema tests plus opt-in Ghidra compile/headless coverage
• add CI matrix compiling scripts against Ghidra 11.0, 11.4.2, and 12.1 release jars

Verification

• PYTHONPATH=src pytest tests/test_ghidra2isf.py tests/test_loader_paths.py -q
• PYTHONPATH=src python3 -m compileall -q src/dwarffi tests/test_ghidra2isf.py
• python3 -c "import yaml, pathlib; yaml.safe_load(pathlib.Path('.github/workflows/ci.yml').read_text()); print('yaml ok')"
• local javac compile against Ghidra 11.0, 11.4.2, and 12.1 release jars