fix(extension): open file chooser for hidden file inputs on upload

[yapxue]

Problem

set-file-input fails whenever the target file input is hidden, e.g. on the Xiaohongshu creator center:

Image injection failed: Page.fileChooserOpened not received within 5s — the input may not have opened a file chooser

This breaks opencli xiaohongshu publish and opencli browser <session> upload for those sites.

Repro:

opencli browser xhs open "https://creator.xiaohongshu.com/publish/publish?from=menu_left&target=image"
opencli browser xhs eval "(()=>{const i=document.querySelector('.upload-input');const r=i.getBoundingClientRect();return JSON.stringify({w:r.width,h:r.height,display:getComputedStyle(i).display});})()"
# {"w":0,"h":0,"display":"block"}
opencli browser xhs upload ".upload-input" "/path/to/any.jpg"
# x Page.fileChooserOpened not received within 5s

Root cause

DOM.setFileInputFiles is rejected under chrome.debugger (crbug 928255), so the extension opens the chooser via Page.setInterceptFileChooserDialog + Runtime.evaluate .click() and uses the backendNodeId from Page.fileChooserOpened. The chooser only opens for a rendered input and when the click carries a user gesture. A 0x0 hidden input (hidden <input type=file> behind a styled button - a very common pattern) never opens a chooser, so the event never fires and the call times out.

Fix

Before clicking, if the input is not rendered (display:none / visibility:hidden / opacity:0 / zero rect), temporarily reveal it (fixed 1x1 box) and click with Runtime.evaluate userGesture: true; restore the original inline style in finally.

Tests

Added a cdp setFileInputFiles unit test covering the reveal -> click(userGesture) -> restore flow and the DOM.setFileInputFiles backendNodeId hand-off. I could not run vitest locally in this environment (no node_modules, slow network); please rely on CI.

[yapxue]

Pushed a fix for the failing extension test: the mock needed chrome.debugger.onEvent.removeListener (called by the cleanup path). The audit failure is unrelated to this change — it is a pre-existing js-yaml advisory (GHSA-2883-xcg3-v3hh) flagged by npm audit --omit=dev on the base tree.