feat(db): add postgresql support

internal/assets/migrations/postgres/000001_init_postgres.up.sql

@@ -0,0 +1,10 @@
+CREATE TABLE IF NOT EXISTS "sessions" (
+    "uuid"         TEXT    NOT NULL PRIMARY KEY,
+    "username"     TEXT    NOT NULL,
+    "email"        TEXT    NOT NULL,
+    "name"         TEXT    NOT NULL,
+    "provider"     TEXT    NOT NULL,
+    "totp_pending" BOOLEAN NOT NULL,
+    "oauth_groups" TEXT    NOT NULL DEFAULT '',
+    "expiry"       BIGINT  NOT NULL
+);