feat: add tabs.create support in bridge extension

[wangjc683]

Summary

Restore the ability to open new browser tabs, lost after f0ff7ee removed TMWebDriver.newtab() (which relied on Tampermonkey GM_openInTab).

Changes

assets/tmwd_cdp_bridge/background.js (+6 lines)

• Add create method to the tabs command handler in handleExtMessage
• Calls chrome.tabs.create() with url and active options
• Returns new tab info: { id, url, title, windowId }

TMWebDriver.py (+6 lines)

• Add newtab(url=None, active=True) method
• Serializes {cmd:"tabs", method:"create", ...} and routes through existing execute_js() → WS → bridge path
• Reuses any active ext_ws session WebSocket connection

Testing

All scenarios passed (8 tabs created):

• ✅ Open tab with active=False (background)
• ✅ Open tab with active=True (foreground)
• ✅ Open duplicate URLs (creates separate tabs)
• ✅ Rapid consecutive opens (no race conditions)
• ✅ Tested: baidu, bing, github, hackernews, zhihu, douban, bilibili