feat: vm name, mount_project, ubuntu-24.04, provision scripts, copy command, workdir

[saeta-eth]

Summary

• [vm] name — fixed VM name overriding the hash-derived watermelon-{project}-{hash} default; enables targeting the same VM from any directory
• [vm] mount_project — opt-out of bind-mounting the project dir into /project (defaults true via *bool); needed for VM-as-environment setups like the dev Docker host
• [vm] image — adds ubuntu-24.04 support alongside the existing ubuntu-22.04 default
• [provision] scripts — shell scripts to embed and run as root during provisioning; paths relative to project dir or absolute
• [ide] workdir — override the remote directory opened by watermelon code
• watermelon copy — new command wrapping limactl copy for host↔VM file transfer (-r for recursive)
• --name flag on all commands (run, exec, stop, destroy, status, code, logs)
• --workdir flag on watermelon run
• VM name resolution order: --name flag → [vm] name in config → hash-derived fallback

Test plan

• go test ./... passes (all new behaviour covered by unit tests)
• watermelon run --name somospollo-vm targets a fixed-name VM without a config file
• Config with mount_project = false generates Lima YAML with mounts: []
• Config with image = "ubuntu-24.04" generates correct Lima image URLs
• [provision] scripts content is embedded verbatim into Lima YAML provision blocks
• watermelon copy ./file.txt myvm:/tmp/ and watermelon copy -r ./dir/ myvm:/tmp/ work end-to-end
• watermelon code opens IDE at [ide] workdir when set