feat(server): host schema, context, auth, status transitions

server/priv/repo/migrations/20260421200116_create_hosts.exs

@@ -0,0 +1,19 @@
+defmodule Server.Repo.Migrations.CreateHosts do
+  use Ecto.Migration
+
+  def change do
+    create table(:hosts) do
+      add :name, :string, null: false
+      add :token_hash, :string, null: false
+      add :agent_version, :string
+      add :proxmox_version, :string
+      add :zfs_version, :string
+      add :status, :string, null: false, default: "never_connected"
+      add :last_seen_at, :utc_datetime_usec
+
+      timestamps(type: :utc_datetime_usec)
+    end
+
+    create unique_index(:hosts, [:name])
+  end
+end