fix: add x86_64-unknown-linux-musl build target for npm install (#112)

When glibc isn't compatible (Alpine, NixOS, Docker scratch images),
the npm install script falls back to a static musl binary. However,
no musl target was configured in dist-workspace.toml, causing the
fallback to fail with "Platform not supported".

Fixes #86

.changeset/fix-linux-musl-install.md

@@ -0,0 +1,5 @@
+---
+"@googleworkspace/cli": patch
+---
+
+Add `x86_64-unknown-linux-musl` build target for Linux musl/static binary support

dist-workspace.toml

@@ -30,7 +30,7 @@ npm-scope = "@googleworkspace"
 github-attestations = true
 npm-package = "cli"
 # Target platforms to build apps for (Rust target-triple syntax)
-targets = ["aarch64-apple-darwin", "aarch64-unknown-linux-gnu", "aarch64-unknown-linux-musl", "x86_64-apple-darwin", "x86_64-unknown-linux-gnu", "x86_64-pc-windows-msvc"]
+targets = ["aarch64-apple-darwin", "aarch64-unknown-linux-gnu", "aarch64-unknown-linux-musl", "x86_64-apple-darwin", "x86_64-unknown-linux-gnu", "x86_64-unknown-linux-musl", "x86_64-pc-windows-msvc"]
 # Which actions to run on pull requests
 pr-run-mode = "plan"
 # Don't overwrite release.yml on `cargo dist init` (preserves custom npm registry config)