Feat: Add Linux support via QEMU tap networking

[bdkabiruddin]

Description

This PR addresses issue #599 by enabling trellis-cli to work on Linux using Lima with QEMU.

Currently, trellis-cli relies on vmType: vz and macOS-specific networking, which makes VMs inaccessible on Linux (cannot route to the VM's IP).

Changes Implemented

1. Dynamic VM Type

• Updated pkg/lima/instance.go and config.yml to switch between vz (macOS) and qemu (Linux).

2. Bridged Networking (The "TAP" Solution)

Since Lima on Linux (QEMU) implies user-mode networking by default, I implemented a bridged network approach:

• Host Side: The CLI automatically checks for and creates a tap0 interface (assigned 192.168.56.1) on the host using sudo.
• VM Side: A provision script creates a corresponding interface inside the VM assigned to 192.168.56.5.

3. QEMU Wrapper

Lima does not currently expose a way to inject specific -netdev tap arguments.

• Implemented a temporary qemu-system-x86_64 wrapper script in pkg/lima/manager.go.
• This script injects the TAP network device arguments before passing control to the real QEMU binary.

4. IP Detection

• Updated Instance.IP() to prioritize the custom bridged subnet (192.168.56.x) on Linux.
• Falls back to the default NAT IP if the bridge is missing or if running on macOS.

Verification

• Tested on Ubuntu 22.04.
• Confirmed macOS logic remains untouched via runtime.GOOS checks.