feat: Align note display with code indentation

[ushmz]

Summary

Improved the visual alignment of note displays by matching the indentation of the code they're attached to.

Changes:

• Note virtual lines now use the same indentation as the target line
• Removed "Note: " prefix for cleaner, more minimal display
• Notes visually blend with the code structure while remaining distinct through highlighting

Visual comparison

Before:

Note: This is a function
      Second line of note
    function foo()
      local x = 1
    end

After:

    This is a function
    Second line of note
    function foo()
      local x = 1
    end

Implementation

Modified display_note_as_virtual_line() in lua/tabi/ui/display.lua:

• Extract leading whitespace from the target line using pattern matching (^%s*)
• Apply the same indentation to all virtual line content
• Removed conditional prefix logic

Test plan

• All 364 existing tests pass
• luacheck and stylua checks pass
• Manual testing: Notes align correctly with various indentation levels
• Manual testing: Multi-line notes maintain consistent indentation