Add diagnostics pane and optimize with line indexing

[simwai]

This change introduces a diagnostic system and performance optimizations to the babae TUI editor.

Key enhancements:

• Diagnostic Pane: A new live diagnostic view can be toggled using Ctrl+D. This provides real-time visibility into internal events (input handling, clipboard errors, etc.) without corrupting the main editor rendering.
• Performance Optimization: Buffer offset-to-row conversions are now backed by a binary-searched line-start index ($script:lineIndex). This improves performance for large files by replacing O(n) scans with O(log n) lookups.
• Mouse Support: Added support for mouse events (ANSI modes ?1000h, ?1003h, ?1006h), specifically allowing users to drag the diagnostic pane divider to resize the pane.
• Improved Error Handling: Swallowed exception paths in installation, input threads, and clipboard operations have been replaced with logging to the diagnostic ring buffer and optional debug log file.
• Configuration: Added -DiagPane and -DebugLog parameters to the main script.

All buffer mutation points (Enter, Backspace, Delete, Tab, Paste, printable characters) have been updated to maintain the line-start index. Existing Pester tests pass, and the new logic has been manually verified for correctness.

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PR created automatically by Jules for task 7894184619913533842 started by @simwai

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