fix(lsp): biome bunx fallback runs the unrelated biome npm package instead of @biomejs/biome #133

Problem

When neither node_modules/.bin/biome nor a biome on PATH is found, BiomeServer.spawn falls back to:

spawn('bunx', ['biome', 'lsp-proxy', '--stdio'], …)

(packages/lsp/src/server/biome.ts:75)

bunx biome resolves the npm package named biome. That is not Biome. Biome is published as @biomejs/biome. The unscoped biome package is an unrelated project ("A simple way to manage environment variables on a per-project basis", latest 0.3.3), and it also ships a biome bin:

So on a machine without Biome installed, the fallback downloads and runs an unrelated third-party package with lsp-proxy --stdio. The Biome language server never starts. Instead, the LSP client gets a process that does not speak LSP. The warning in the catch block already says the right package (npm install @biomejs/biome), but the spawn itself uses the wrong one.

Expected

The fallback runs the real Biome CLI. For example:

spawn('bunx', ['@biomejs/biome@<version>', 'lsp-proxy', '--stdio'], …)

Pin the version, the way the TypeScript fallback pins typescript-language-server@4.3.3 since #131. That keeps the fallback reproducible, and stops it from reusing whatever the bare name resolves to.

Notes

• spawn from node:child_process reports a missing command through the async error event; it does not throw synchronously. So the catch around the bunx fallback, and its install hint, effectively never run. The fix may want to log the hint some other way.
• The real-package resolution could be covered by a test like the classic-fallback tests added in fix(lsp): skip an unrunnable typescript-language-server and fall back to bunx #131 (packages/lsp/test/unit/server.test.ts). Those tests put a recording bunx on PATH and assert its arguments.

Found while working on #127 / #131.