Function analyzeOpenDocuments

Analyzes ALL open documents (notebooks AND lexicals) in VS Code workspace.

Smart detection approach:

• Checks vscode.window.tabGroups to get all open documents including custom editors.
• Distinguishes native VS Code notebooks from Datalayer local documents.
• Detects cloud Datalayer documents (notebooks + lexicals) via datalayer:// URI scheme.
• Includes lexical documents in the analysis for complete context.