Lataa GitButler 0.18.0

## Codegen
- Prompting is now done directly from the workspace (for a specific branch). The Codegen tab on the left has been removed
- The chat UX has been updated for better ergonomics and better display of tool calls
- Updated permissions system - better granularity and control for what the agent can perform
- Prompt history can now be accessed via arrow up / down of the input
- The prompt input has improved rendering for code snippets and referenced files
- Files and commits from the workspace can be dragged into prompts to reference them

## Changes
- The "Create Branch" button has been moved to the top right of the app
- When creating a branch there is now the option to have it placed in the left-most position
- In lists of files (e.g. uncommitted) it is now possible to select all (with Cmd+A)
- Release notes (when updating) can now display of previous release notes
- Added syntax highlighting for .cc files

## Fixes
- Fixes an issue with repository auto-fetch
- Fixes a bug allowing for stale selection in the UI after a branch is deleted

## CLI
- Added `but .` or `but /path/to/repo` which opens the GitButler app for the provided path
- `but status` now shows additional upstream data
- `but status` now shows worktree information if applicable
- `but status --json` output has been simplified for better scriptability
- `but log` has been removed (as its functionality overlapped with status)
- Fixes an issue where in some cases `but rub` would run into ID ambiguity unnecessarily