Allow `ˆ` modifier work on line content in `buf_lines` picker

Contributing guidelines

• I have read CONTRIBUTING.md
• I have read CODE_OF_CONDUCT.md
• I have updated 'mini.nvim' to latest version of the main branch

Module(s)

mini.pick

Neovim version

0.11.x

Description

Hello, I have a small issue with the Pick module, and I'm not sure if I'm doing something wrong. Basically, I want to use Pick buf_lines scope="current" to search for specific lines in the current buffer. Specifically, I want to find all lines that start with 'j' followed by a space. Trying with "^j " doesn't work because the line is interpreted as starting with the line number, so the ^ modifier seems less useful in this case. Am I doing something wrong? Is there a way to remove line numbers from the picker's selection window? I know I can use a search or vimgrep to get the same result, but using buf_lines mode is simpler and faster. Thank you very much for your help.

Reproduction

1. Create separate 'nvim-repro' config directory:

   • '~/.config/nvim-repro/' on Unix
   • '~/AppData/Local/nvim-repro/' on Windows

2. Inside 'nvim-repro' directory create a file named 'init.lua'.
   Populate it with the following content:

   -- Clone latest 'mini.nvim' (requires Git CLI installed)
   vim.cmd('echo "Installing `mini.nvim`" | redraw')
   local mini_path = vim.fn.stdpath('data') .. '/site/pack/deps/start/mini.nvim'
   local clone_cmd = { 'git', 'clone', '--depth=1', 'https://github.com/echasnovski/mini.nvim', mini_path }
   vim.fn.system(clone_cmd)
   vim.cmd('echo "`mini.nvim` is installed" | redraw')
   
   -- Make sure 'mini.nvim' is available
   vim.cmd('packadd mini.nvim')
   require('mini.deps').setup()
   
   -- Add extra setup steps needed to reproduce the behavior
   -- Use `MiniDeps.add('user/repo')` to install another plugin from GitHub
   

3. Run NVIM_APPNAME=nvim-repro nvim (i.e. execute nvim with NVIM_APPNAME environment variable set to "nvim-repro").
   Wait for all dependencies to install.

4. Replace this with description of interactive reproduction steps along with the behavior you observe.
   Feel free to include images/videos/etc, this helps a lot.

Start with the mini.pick implementation for the Pick buf_lines source and its handling of the ^ modifier and displayed line numbers. Reproduce the search for ^j with scope="current"; done means the modifier can match line content from the beginning of a buffer line without requiring users to account for the picker’s line-number prefix.