feat(nvim): Add Ctrl+A + space to reset DAP screens to original size

## Feature Request

### Description
Add a keybinding (Ctrl+A + space) to reset DAP UI windows to their original size, similar to how tmux allows resetting pane layouts.

### Current Behavior
When debugging with DAP in Neovim, the UI panels (variables, stack, watches) can be resized manually, but there's no quick way to reset them to their default sizes.

### Desired Behavior
- Pressing Ctrl+A followed by space should reset all DAP UI panels to their original/default sizes
- This mimics tmux's behavior where the same key combination resets pane layouts

### Implementation Details
- Add a new keybinding in the DAP configuration
- The keybinding should call a function that resets the DAP UI layout
- This should work regardless of which DAP UI panels are currently visible

### Benefits
- Improves workflow when debugging
- Provides consistency with tmux keybindings (muscle memory transfer)
- Helps recover from accidentally resized panels

### References
- Current DAP keybindings are documented in
- Similar functionality exists in tmux as documented in

### Priority
Medium - Quality of life improvement for debugging workflows

Start by locating the Neovim DAP configuration and the existing DAP keybindings. Trace how the current panels are opened and resized, then verify that Ctrl+A followed by space resets all visible DAP UI panels to their default sizes.

Written by the indexing model from the issue text.