feat(nodes): per-node default domain with auto service hostnames (#65)

node_agents.default_domain gives each agent a base domain. Services
placed on it (explicit pin or spread) with no explicit service_domains
get <name>.<default_domain> — resolved in serviceDomainNames so edge
routing, wake placeholders, and public_url all see the same names.
Spread services union every eligible node's base domain; explicit
domains always win.

Surfaces: PUT /agents/:id {default_domain} (hostname-validated), CLI
nodes update --domain, MCP arg docs, OpenAPI + regenerated types,
node-detail inline editor.

Also marks the already-shipped backup-import roadmap item.

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Co-authored-by: Devin <158243242+devin-ai-integration[bot]@users.noreply.github.com>

app/frontend/src/generated/api-types.ts

@@ -8179,7 +8179,7 @@ export interface paths {
         };
         /**
          * Update node agent
-         * @description Partial update — accepts any subset of agent fields (name, status, auto_prune, tags). `tags` sets the node's placement labels; services with placement_tags only schedule onto agents carrying every required tag.
+         * @description Partial update — accepts any subset of agent fields (name, status, auto_prune, tags, default_domain). `tags` sets the node's placement labels; services with placement_tags only schedule onto agents carrying every required tag. `default_domain` gives the node a base domain — domainless services placed there get `<name>.<default_domain>` auto-hostnames; empty string clears it.
          */
         put: {
             parameters: {
@@ -12297,6 +12297,8 @@ export interface components {
             schedulable?: boolean;
             /** @description Operator-set placement labels; services with placement_tags require all of them on the target node. */
             tags?: string[];
+            /** @description Node base domain — services placed on this node (pin or spread) with no explicit service_domains get `<name>.<default_domain>` hostnames automatically. Wildcard DNS for `*.<default_domain>` must resolve to the Containr edge. */
+            default_domain?: string;
             /** Format: date-time */
             last_heartbeat?: string;
             /** Format: date-time */