init: scaffold from k-template with postgres + worker

crates/adapters/postgres/migrations/001_init_users.sql

@@ -0,0 +1,7 @@
+CREATE TABLE IF NOT EXISTS users (
+    id            UUID PRIMARY KEY NOT NULL,
+    email         TEXT UNIQUE NOT NULL,
+    password_hash TEXT NOT NULL,
+    role          TEXT NOT NULL DEFAULT 'user',
+    created_at    TIMESTAMPTZ NOT NULL DEFAULT NOW()
+);