refactor: replace gorm with vanilla sql and sqlc

schema.sql

@@ -0,0 +1,11 @@
+CREATE TABLE IF NOT EXISTS "sessions" (
+    "uuid" TEXT NOT NULL PRIMARY KEY UNIQUE,
+    "username" TEXT NOT NULL,
+    "email" TEXT NOT NULL,
+    "name" TEXT NOT NULL,
+    "provider" TEXT NOT NULL,
+    "totp_pending" BOOLEAN NOT NULL,
+    "oauth_groups" TEXT NULL,
+    "expiry" INTEGER NOT NULL,
+    "oauth_name" TEXT NULL
+);