Refactor import statements in webui_manager.py

[dhantlaharika-ctrl]

Summary by cubic

Updated imports in webui_manager.py to use top-level exports from browser_use (Browser, BrowserContext) instead of deep module paths. This simplifies the code and aligns with the package’s public API with no behavior changes.

^{Written for commit 5da70aa. Summary will update on new commits.}

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[cubic-dev-ai]

No issues found across 1 file

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