Add optional newline before Insert After operations

[chhoumann]

Summary

Add an option to automatically insert a newline before content when using "Insert After" mode in captures.

Problem

When using "Insert After" captures:

• Content is inserted immediately after the target line
• No spacing between existing content and new content
• Results in poor formatting and readability
• Users must manually add newlines to their capture format

Current Behavior

Existing line
New content immediately follows

Desired Behavior

Existing line

New content with proper spacing

Proposed Solution

Add checkbox option in Capture Choice settings:

• "Add newline before insert"
• When enabled, automatically prepends a newline character before captured content
• Works with all Insert After operations
• Preserves existing capture format syntax

Implementation

• Simple string prepending: \n + capture content
• Setting saved per Capture Choice
• No impact on other insert modes
• Compatible with existing templates

Benefits

• Better formatted output
• Improved readability
• Consistent spacing in captured content
• Less manual format tweaking required

Related Issues

• Insert After has various formatting challenges (#742, #712)
• This would improve overall Insert After user experience