Package Muse Code for OPR

[dhh]

Add muse-code 1.0.3.r2198.1 to OPR so Omarchy can offer Meta's coding agent without an AUR installation. The package downloads Meta's versioned, statically linked x86_64 and ARM64 binaries, verifies pinned SHA-256 checksums, and installs the native command at /usr/bin/muse.

Uses local-source metadata on the fast release ring. Declares conflicts with the AUR variants and Arch's unrelated MusE sequencer, which also owns /usr/bin/muse. Ships the upstream binary directly, without the AUR package's session/MCP wrappers. Updates are manually pinned; there is no AUR sync dependency.

Companion integration: omacom/omarchy#9915. That PR will install muse-code through omarchy-pkg-add once this package is published.

Validation:

• Built both architecture packages locally with makepkg and verified their contents and package metadata. The ARM64 build repackages the vendor binary; it was not executed on ARM hardware.
• Both vendor downloads match the pinned checksums.
• Extracted x86_64 package reports Muse Code 1.0.3 (1.0.3-R2198.1).
• OPR metadata discovery lists it as a local fast-ring package; Bash syntax and diff checks pass.

No package has been signed or published by this PR.