v0.1.25 — Intel + Apple Silicon

Intel support — one formula, both architectures

This release adds darwin-x64 artifacts alongside darwin-arm64. The Homebrew
formula now carries on_arm/on_intel blocks, so brew install androidStern/nutshell/nutshell automatically installs the right build for the
host. The formula declares depends_on macos: :sonoma — the true floor of the
shipped binaries (Swift deployment target macosx14.0); brew refuses cleanly on
older systems instead of installing an app that cannot launch.

Product changes: none — the product source is identical to v0.1.24 apart
from the version string. This is a packaging release: per-arch build pipeline
(Bun cross-compile with the baseline x64 target, since Rosetta lacks AVX;
swiftc -target per arch; per-arch signing), dual-tarball + dual-SHA formula
generation, and certification that verifies both architectures including a
real Rosetta smoke run of the Intel CLI and app.

Validation status: v0.1.24's full gate ledger (imports, signed-out,
signed-in, permissions-pre, permissions-post, live-sync/dashboard — all PASS)
carries to the product behavior, which is unchanged. The arm64 artifact is
certified identically to v0.1.24. The x64 artifact is certified and
Rosetta-smoked; it has not run on physical Intel hardware yet — the first
Intel install will be its first real-hardware validation. Dependency
fence: unchanged (host bun upgraded 1.3.6→1.3.14 to fix a bun codesigning
bug affecting re-signed x64 binaries; bun is an approved host tool).
Install paths: Homebrew and tarball; npm deferred.