Add server commands with extensible provider support (#619)

Introduce a new provider abstraction layer in pkg/server that enables
support for multiple cloud providers. This refactor:

- Adds Provider and DNSProvider interfaces for cloud operations
- Implements DigitalOcean provider using the new abstraction
- Adds `trellis server create` command to replace `trellis droplet create`
- Adds `trellis server dns` command to replace `trellis droplet dns`
- Marks existing `droplet` commands as deprecated
- Adds deprecatedCommandHelpFunc to show deprecated commands separately
- Updates default image to Ubuntu 24.04
- Adds server.provider config option in trellis.cli.yml

The provider can be configured via:
1. --provider flag
2. TRELLIS_SERVER_PROVIDER environment variable
3. server.provider in trellis.cli.yml

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-authored-by: Claude Opus 4.5 <noreply@anthropic.com>

Author: swalkinshaw

cli_config/cli_config.go

@@ -25,6 +25,10 @@ type VmConfig struct {
 	ForwardHttpPort bool      `yaml:"forward_http_port"`
 }
 
+type ServerConfig struct {
+	Provider string `yaml:"provider"`
+}
+
 type Config struct {
 	AllowDevelopmentDeploys bool              `yaml:"allow_development_deploys"`
 	AskVaultPass            bool              `yaml:"ask_vault_pass"`
@@ -34,6 +38,7 @@ type Config struct {
 	Open                    map[string]string `yaml:"open"`
 	VirtualenvIntegration   bool              `yaml:"virtualenv_integration"`
 	Vm                      VmConfig          `yaml:"vm"`
+	Server                  ServerConfig      `yaml:"server"`
 }
 
 var (
@@ -73,6 +78,10 @@ func (c *Config) LoadFile(path string) error {
 		return fmt.Errorf("%w: unsupported value for `database_app`. Must be one of: tableplus, sequel-ace", InvalidConfigErr)
 	}
 
+	if c.Server.Provider != "" && c.Server.Provider != "digitalocean" {
+		return fmt.Errorf("%w: unsupported value for `server.provider`. Must be one of: digitalocean", InvalidConfigErr)
+	}
+
 	return nil
 }
 

cmd/droplet_create.go

@@ -50,6 +50,9 @@ func (c *DropletCreateCommand) init() {
 }
 
 func (c *DropletCreateCommand) Run(args []string) int {
+	c.UI.Warn("DEPRECATED: 'trellis droplet create' is deprecated. Use 'trellis server create' instead.")
+	c.UI.Warn("This command will be removed in a future version.\n")
+
 	if err := c.Trellis.LoadProject(); err != nil {
 		c.UI.Error(err.Error())
 		return 1

cmd/droplet_dns.go

@@ -38,6 +38,9 @@ func (c *DropletDnsCommand) init() {
 }
 
 func (c *DropletDnsCommand) Run(args []string) int {
+	c.UI.Warn("DEPRECATED: 'trellis droplet dns' is deprecated. Use 'trellis server dns' instead.")
+	c.UI.Warn("This command will be removed in a future version.\n")
+
 	if err := c.Trellis.LoadProject(); err != nil {
 		c.UI.Error(err.Error())
 		return 1