v0.0.5: build: strip .pdb files from the macOS bundle before signing

codesign treats every file alongside a signed Mach-O as a nested
subcomponent and aborts the bundle seal when it encounters one that is
not itself signable (e.g. a .NET debug symbol file).  Delete *.pdb from
Contents/MacOS as part of packaging so the subsequent sign step can
seal the bundle cleanly.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>