feat: refresh webview after applying AI code changes

[devin-ai-integration]

This PR implements automatic webview refresh after AI code changes are applied.

Changes

• Added webview refresh after code changes are applied in ChatCodeManager.applyCode
• Uses refreshAstDoc to ensure the AST is updated after DOM changes
• Only refreshes selected webviews to avoid unnecessary updates

Link to Devin run: https://app.devin.ai/sessions/b7271ca980ca4364931ade443baafedc

[devin-ai-integration]

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