fix(startup): omit Linux-only package mgrs from PATH on non-Linux

Snap and Linuxbrew don't ship installers for Darwin or BSD, so seeding
their PATH entries on those platforms adds phantom directories every
spawn must stat. Keep them on Linux only, while preserving Nix and
Homebrew across all platforms as they have multi-platform support.

src/main/startup/configure-process.test.ts

@@ -77,6 +77,66 @@ describe('patchPackagedProcessPath', () => {
     expect(segments).toContain(join('/Users/tester', 'bin'))
   })
 
+  it('omits Linux-only snap/Linuxbrew dirs but keeps Nix on packaged darwin runs', async () => {
+    const { app } = await import('electron')
+    const { patchPackagedProcessPath } = await import('./configure-process')
+
+    setPlatform('darwin')
+    Object.defineProperty(app, 'isPackaged', { configurable: true, value: true })
+    process.env.HOME = '/Users/tester'
+    process.env.PATH = '/usr/bin:/bin'
+
+    patchPackagedProcessPath()
+
+    const segments = (process.env.PATH ?? '').split(':')
+    // Why: neither has a macOS installer, so both are phantom PATH entries.
+    expect(segments).not.toContain('/snap/bin')
+    expect(segments).not.toContain('/home/linuxbrew/.linuxbrew/bin')
+    // Why: Nix does ship a macOS default profile, so it stays seeded.
+    expect(segments).toContain('/nix/var/nix/profiles/default/bin')
+    expect(segments).toContain('/opt/homebrew/bin')
+    expect(segments).toContain('/usr/local/bin')
+  })
+
+  it('keeps snap, Linuxbrew, and Nix dirs for packaged linux runs', async () => {
+    const { app } = await import('electron')
+    const { patchPackagedProcessPath } = await import('./configure-process')
+
+    setPlatform('linux')
+    Object.defineProperty(app, 'isPackaged', { configurable: true, value: true })
+    process.env.HOME = '/home/tester'
+    process.env.PATH = '/usr/bin:/bin'
+
+    patchPackagedProcessPath()
+
+    const segments = (process.env.PATH ?? '').split(':')
+    expect(segments).toContain('/snap/bin')
+    expect(segments).toContain('/home/linuxbrew/.linuxbrew/bin')
+    expect(segments).toContain('/nix/var/nix/profiles/default/bin')
+    expect(segments.indexOf('/usr/local/sbin')).toBeLessThan(segments.indexOf('/snap/bin'))
+    expect(segments.indexOf('/home/linuxbrew/.linuxbrew/bin')).toBeLessThan(
+      segments.indexOf('/nix/var/nix/profiles/default/bin')
+    )
+  })
+
+  it('omits snap/Linuxbrew but keeps Nix on non-Linux POSIX platforms', async () => {
+    const { app } = await import('electron')
+    const { patchPackagedProcessPath } = await import('./configure-process')
+
+    setPlatform('freebsd')
+    Object.defineProperty(app, 'isPackaged', { configurable: true, value: true })
+    process.env.HOME = '/home/tester'
+    process.env.PATH = '/usr/bin:/bin'
+
+    patchPackagedProcessPath()
+
+    const segments = (process.env.PATH ?? '').split(':')
+    expect(segments).not.toContain('/snap/bin')
+    expect(segments).not.toContain('/home/linuxbrew/.linuxbrew/bin')
+    expect(segments).toContain('/nix/var/nix/profiles/default/bin')
+    expect(segments).toContain('/usr/local/bin')
+  })
+
   it('leaves PATH untouched when the app is not packaged', async () => {
     const { app } = await import('electron')
     const { patchPackagedProcessPath } = await import('./configure-process')

src/main/startup/configure-process.ts

@@ -99,15 +99,14 @@ export function patchPackagedProcessPath(): void {
   const extraPaths: string[] = []
 
   if (process.platform !== 'win32') {
-    extraPaths.push(
-      '/opt/homebrew/bin',
-      '/opt/homebrew/sbin',
-      '/usr/local/bin',
-      '/usr/local/sbin',
-      '/snap/bin',
-      '/home/linuxbrew/.linuxbrew/bin',
-      '/nix/var/nix/profiles/default/bin'
-    )
+    extraPaths.push('/opt/homebrew/bin', '/opt/homebrew/sbin', '/usr/local/bin', '/usr/local/sbin')
+
+    if (process.platform === 'linux') {
+      // Why: snap and Linuxbrew ship on Linux only, so seeding them elsewhere adds phantom PATH entries every spawn must stat.
+      extraPaths.push('/snap/bin', '/home/linuxbrew/.linuxbrew/bin')
+    }
+
+    extraPaths.push('/nix/var/nix/profiles/default/bin')
 
     if (home) {
       extraPaths.push(