Add auto-generated subdomain feature

When a base domain is configured on a host (e.g., apps.example.com),
deployments automatically get a subdomain ({name}.apps.example.com).
Custom --domain can still be provided to route both domains.

- Add BaseDomain field to Host state
- Add --base-domain flag to host init
- Add 'ship host set-domain' command to update base domain
- Update deploy flow to auto-generate subdomains
- Fix error display (errors were being silently swallowed)
- Remove placeholder email from Caddyfile template

1 files changed, 3 insertions, 2 deletions

diff --git a/internal/state/state.go b/internal/state/state.go
index b99e4ca..c6de34a 100644
--- a/internal/state/state.go
+++ b/internal/state/state.go
@@ -15,8 +15,9 @@ type State struct {
 
 // Host represents deployment state for a single VPS
 type Host struct {
-        NextPort int             `json:"next_port"`
-        Apps     map[string]*App `json:"apps"`
+        NextPort   int             `json:"next_port"`
+        BaseDomain string          `json:"base_domain,omitempty"`
+        Apps       map[string]*App `json:"apps"`
 }
 
 // App represents a deployed application or static site