feat: add worker distributor and model registry

internal/persistence/migrations/001_create_initial.up.sql

@@ -1,4 +1,22 @@
 CREATE TABLE worker_register (
-    worker_id UUID PRIMARY KEY NOT NULL
+      worker_id UUID PRIMARY KEY NOT NULL
+    , capacity INTEGER NOT NULL
     , heart_beat TIMESTAMPTZ NOT NULL DEFAULT now()
 );
+
+CREATE TABLE model_schedules (
+      model_name TEXT PRIMARY KEY NOT NULL
+    , last_run TIMESTAMPTZ
+);
+
+CREATE TABLE work_schedule (
+      schedule_id UUID PRIMARY KEY NOT NULL
+    , worker_id UUID NOT NULL
+    , start_run TIMESTAMPTZ NOT NULL
+    , end_run TIMESTAMPTZ NOT NULL
+    , updated_at TIMESTAMPTZ NOT NULL DEFAULT now()
+    , state TEXT NOT NULL
+);
+
+CREATE INDEX idx_work_schedule_worker ON work_schedule (worker_id);
+CREATE INDEX idx_work_schedule_worker_updated ON work_schedule (worker_id, updated_at DESC);