auth: cut over community machine access to agent keys

crates/crank-registry/src/migrations.rs

@@ -144,6 +144,7 @@ pub async fn apply_postgres(pool: &PgPool) -> Result<(), sqlx::Error> {
         "create table if not exists platform_api_keys (
             id text primary key,
             workspace_id text not null references workspaces(id) on delete cascade,
+            agent_id text null,
             name text not null,
             prefix text not null,
             secret_hash text not null,
@@ -162,6 +163,9 @@ pub async fn apply_postgres(pool: &PgPool) -> Result<(), sqlx::Error> {
     )
     .execute(pool)
     .await?;
+    query("alter table platform_api_keys add column if not exists agent_id text null")
+        .execute(pool)
+        .await?;
 
     query(
         "insert into workspaces (