Refactor database handling to exclusively support PostgreSQL

- Removed SQLite support from the configuration and database initialization logic.
- Updated database migration scripts to focus solely on PostgreSQL migrations.
- Simplified logging messages to reflect PostgreSQL usage.
- Adjusted database schema definitions to remove SQLite-specific types and structures.
- Modified tests to ensure compatibility with PostgreSQL, including changes to table creation and data types.
- Cleaned up unused imports and code related to SQLite.

drizzle.config.ts

@@ -1,24 +1,18 @@
 import { defineConfig } from "drizzle-kit";
 
-const databaseType = process.env.DATABASE_TYPE || "sqlite";
 const databaseUrl = process.env.DATABASE_URL;
 
 export default defineConfig({
   schema: "./src/database/schema.ts",
   out: "./drizzle/migrations",
-  dialect: databaseType === "postgres" ? "postgresql" : "sqlite",
-  dbCredentials:
-    databaseType === "postgres"
-      ? databaseUrl
-        ? { url: databaseUrl }
-        : {
-            host: process.env.POSTGRES_HOST || "localhost",
-            port: parseInt(process.env.POSTGRES_PORT || "5432", 10),
-            user: process.env.POSTGRES_USER || "postgres",
-            password: process.env.POSTGRES_PASSWORD || "",
-            database: process.env.POSTGRES_DB || "moderation_bot",
-          }
-      : {
-          url: "file:./.muxer-queue.db",
-        },
+  dialect: "postgresql",
+  dbCredentials: databaseUrl
+    ? { url: databaseUrl }
+    : {
+        host: process.env.POSTGRES_HOST || "localhost",
+        port: parseInt(process.env.POSTGRES_PORT || "5432", 10),
+        user: process.env.POSTGRES_USER || "postgres",
+        password: process.env.POSTGRES_PASSWORD || "",
+        database: process.env.POSTGRES_DB || "moderation_bot",
+      },
 });