v0.7.9

fix(x): stage only the current platform's node-pty prebuilds

Every build shipped all platforms' prebuilt binaries. Windows code
signing walks every .node file in the app and signtool hard-fails on
the Mach-O darwin pty.node ("file format cannot be signed"). Filtering
to the host platform fixes signing and drops dead weight from all
installers. The Linux CI-compiled prebuild and the node-gyp self-heal
path both still stage correctly.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>