feat: project actions

[matt2e]

Summary

Introduces a project actions system that lets users configure and run common development tasks (lint, test, format, build) directly from the branch UI, with optional AI-powered detection to auto-discover available commands from project files.

Changes

Actions Infrastructure

• Adds project_actions database schema to store per-project action configurations with type categorization (prerun, run, build, format, check, test, cleanUp)
• Implements action runner that executes commands in the worktree directory with proper shell environment, streaming output via Tauri events
• Supports auto-commit after successful format/fix actions to streamline the edit-fix-commit workflow
• Adds ANSI color support for terminal output rendering in the UI

AI-Powered Detection

• Integrates with ACP-compatible agents (goose, claude-code-acp) to analyze project structure and suggest relevant actions
• Scans common build files (package.json, justfile, Makefile, Cargo.toml, pyproject.toml) to identify available commands
• Categorizes detected actions by type based on what they actually do (e.g., a "lint" script that auto-fixes is categorized as "format")

UI Integration

• Adds Project Settings modal for managing actions (create, edit, delete, detect)
• Displays action buttons in branch cards grouped by category with submenus for types with 3+ actions
• Shows real-time execution output in a modal with ANSI color rendering, stop/restart controls, and duration tracking
• Prerun actions can be configured to run automatically when creating new worktrees

Technical Details

• Actions are scoped to projects (not branches) so configuration is shared across all branches in a repo
• Output is buffered server-side so opening the output modal mid-execution shows previous output
• Uses libc::kill for proper process termination on Unix systems