test(plugins): run the binary custom-editor e2e on Linux (#35638)

In a hidden Linux test window Playwright's mouse click on a button inside the
sandboxed editor frame never reaches it: the frame takes focus, but no
pointerdown or click fires, so the edit was never sent and the tab never went
dirty. Activate the button from the keyboard instead, which still counts as a
real user gesture.

tests/e2e/plugin-custom-editor.spec.ts

@@ -146,8 +146,6 @@ test('a bytes custom editor edits and saves a binary file', async ({
   orcaPage,
   seededRepoPath
 }) => {
-  // Why: on Linux CI the first bytes edit never marks the tab dirty (passes on macOS); tracked as an alpha follow-up.
-  test.fixme(process.platform === 'linux', 'bytes edit does not reach the tab on Linux CI')
   const pluginRoot = await mkdtemp(join(tmpdir(), 'orca-bytes-editor-'))
   const filePath = join(seededRepoPath, BYTES_FILE)
   // NULs make Orca treat it as binary, like a zip-based workbook.
@@ -198,7 +196,8 @@ test('a bytes custom editor edits and saves a binary file', async ({
     expect(await dirty()).toBe(false)
 
     const append = bytesFrame.locator('#append')
-    await append.click()
+    // Why a key: in a hidden Linux window the mouse never reaches a sandboxed frame's button.
+    await append.press('Enter')
     await expect.poll(dirty).toBe(true)
     await append.press(process.platform === 'darwin' ? 'Meta+s' : 'Control+s')
     const edited = Buffer.concat([original, Buffer.from([0xaa])])