feat: implement project root detection for terminal providers

[horaoen]

fix bug #104

Summary

Fix opencode working directory mismatch when Neovim's actual project directory differs from where nvim was launched.

Problem

When using nvim or navigating to a project via a dashboard plugin, opencode would start in the wrong directory because all providers were inheriting the shell's working directory rather than detecting the actual project root.

Scenarios affected:

• nvim ~/projects/my-app from ~/ → opencode opened in ~/ instead of ~/projects/my-app
• Using dashboard plugins (alpha-nvim, dashboard-nvim) to open projects
• Changing directories with :cd after Neovim starts

Solution

Added get_project_root() function with smart detection priority:

1. Neovim directory argument (nvim )
2. Git root (for git repositories)
3. Current buffer directory (fallback for non-git projects)
4. LSP workspace root (if available)
5. vim.fn.getcwd() (final fallback)

All 5 providers now use this function:

• terminal.lua - Added cwd option to jobstart()
• snacks.lua - Pass cwd to snacks.terminal options
• tmux.lua - Added -c flag to split-window
• wezterm.lua - Added --cwd flag to split-pane
• kitty.lua - Changed from --cwd=current to explicit path

[horaoen]

I have tested it in my environment, and scenarios 1, 2, and 3 all work so far. The implementation for scenario 3 is to close the existing OpenCode workspace and create a new one.

Scene 3

then toggle again

scene 1、2