Database setup for the Website service (#13)

This PR contains the work done to introduce a _Fluent_-based persistence layer for the Website service, selectable at runtime alongside the existing in-memory default, plus the local dev tooling and docs to support it.

To provide further details about the work:

* Persistence package
  * The `Driver` and `TLS` enumerations
  * The `Configuration` type
  * The `Service` factory that builds the  service
  * `PrepareDB` for migrations registration
  * The `Probe` for readiness checks.

* App integration
  *  Builds the driver, registers migrations, and attaches `Fluent` to the service lifecycle so it starts/stops with the HTTP server.
  * Migrate-on-boot is gated to the in-memory backend; MySQL/MariaDB is migrated out of band via --database-migrate so shared databases never race on startup.
  * The `ConfigReader+Properties` extension maps database.* config keys onto the driver.

* Library
  * Added database configuration constants.
  * The `HealthController` controller gains a readiness probe: `GET /health/ready` checks whether the database is reachable, separate from the existing liveness check.

* Others
  * Updated the `docker-compose` files to support a database service behind a database profile, and hardened for local development
  * New database targets on the `Makefile` file and overall documentation updated
  * Updated the `.env.local`, `Dockerfile`, and `README` files to document the persistence workflow, config keys, and local DB commands

Reviewed-on: rock-n-code/loud-amsterdam#13
Co-authored-by: Javier Cicchelli <javier@rock-n-code.com>
Co-committed-by: Javier Cicchelli <javier@rock-n-code.com>

Services/Website/Tests/App/AppTests.swift

@@ -49,6 +49,44 @@ struct AppTests {
         }
     }
 
+    @Test
+    func `health check to be served at the health path`() async throws {
+        try await app(
+            staticFilesPath: staticFilesPath
+        ).test(.router) { client in
+            try await client.execute(
+                uri: "/health",
+                method: .get
+            ) { response in
+                let body = String(buffer: response.body)
+
+                #expect(response.status == .ok)
+                #expect(response.headers[.contentType] == "application/json")
+                #expect(body == #"{"status":"ok"}"#)
+            }
+        }
+    }
+
+    @Test
+    func `readiness check to be served at the readiness path`() async throws {
+        // Live mode runs the application's service group, so the `Fluent` service starts before the
+        // request and shuts its connection pool down after — the router-only mode never would.
+        try await app(
+            staticFilesPath: staticFilesPath
+        ).test(.live) { client in
+            try await client.execute(
+                uri: "/health/ready",
+                method: .get
+            ) { response in
+                let body = String(buffer: response.body)
+
+                #expect(response.status == .ok)
+                #expect(response.headers[.contentType] == "application/json")
+                #expect(body == #"{"status":"ready"}"#)
+            }
+        }
+    }
+
     @Test(arguments: StaticFile.allCases)
     func `static files to be served`(
         staticFile file: StaticFile