fix token totals

[rajbos]

This pull request improves the robustness and accuracy of Copilot token usage tracking and display, especially in the face of evolving API formats and malformed log lines. It introduces better handling for new token reporting formats, adds a regex-based fallback for extracting token usage from corrupted logs, and polishes the webview UI for clarity and consistency.

Token Usage Tracking Improvements:

• Updated the cache version and token extraction logic in CopilotTokenTracker to support new and upcoming API formats, including tokens at result.promptTokens/outputTokens and nested under result.metadata [1] [2] [3] [4] [5].
• Added a regex-based fallback (extractPerRequestUsageFromRawLines) to recover token usage from log lines that fail JSON parsing, ensuring more accurate stats even with malformed logs [1] [2] [3] [4].
• Improved cache key generation in development mode to prevent cache conflicts between VS Code windows by using a unique session-based identifier.

Webview and UI Enhancements:

• Refined the metrics table in the details webview to always show total tokens, regardless of actual usage data availability, making stats more consistent.
• Improved the logviewer UI to clearly display actual token usage per turn and in summary cards, with better formatting and removal of merge conflict artifacts [1] [2].
• Enhanced layout robustness in the logviewer by adjusting word-break behavior for editor and date fields, and by dynamically adjusting the grid layout based on available data [1] [2] [3] [4].