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/middleware/rateLimit.middleware.js

@@ -0,0 +1,21 @@
+const { rateLimit } = require("express-rate-limit");
+
+const response = { success: false, error: { code: "RATE_LIMITED", message: "Too many requests" } };
+
+const generalApiLimiter = rateLimit({
+  windowMs: Number(process.env.API_RATE_LIMIT_WINDOW_MS) || 15 * 60 * 1000,
+  limit: Number(process.env.API_RATE_LIMIT_MAX) || 300,
+  standardHeaders: "draft-8",
+  legacyHeaders: false,
+  message: response,
+});
+
+const sensitiveLimiter = rateLimit({
+  windowMs: Number(process.env.SENSITIVE_RATE_LIMIT_WINDOW_MS) || 15 * 60 * 1000,
+  limit: Number(process.env.SENSITIVE_RATE_LIMIT_MAX) || 20,
+  standardHeaders: "draft-8",
+  legacyHeaders: false,
+  message: response,
+});
+
+module.exports = { generalApiLimiter, sensitiveLimiter };