feat: stabilize API startup and lifecycle management

- Refactor server initialization to separate concerns and improve error handling.
- Implement centralized environment validation using Zod.
- Introduce database, Redis, and queue lifecycle management.
- Add health check endpoints for liveness and readiness.
- Enhance error handling middleware for better response structure.
- Implement rate limiting for API endpoints.
- Add request ID middleware for traceability.
- Create Sequelize CLI configuration and baseline migration for schema management.
- Establish CI workflow with Gitea for testing and syntax checks.
- Document foundational changes and migration strategy in PHASE_0_FOUNDATION_STABILIZATION.md.
- Add Docker Compose configuration for local development and testing.
- Implement unit and integration tests for critical functionality.

app/config/sequelize-cli.config.js

@@ -0,0 +1,17 @@
+require("dotenv").config();
+
+const required = ["DB_HOST", "DB_NAME", "DB_USER"];
+const missing = required.filter((name) => !process.env[name]);
+if (missing.length) throw new Error(`Missing migration environment variables: ${missing.join(", ")}`);
+
+const configuration = {
+  username: process.env.DB_USER,
+  password: process.env.DB_PASSWORD || "",
+  database: process.env.DB_NAME,
+  host: process.env.DB_HOST,
+  port: Number(process.env.DB_PORT || 3306),
+  dialect: "mysql",
+  logging: false,
+};
+
+module.exports = { development: configuration, test: configuration, production: configuration };