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>

Packages/Persistence/Tests/Utils/Fakes/NotSQLDatabase.swift

@@ -0,0 +1,44 @@
+import FluentKit
+
+/// A Fluent database that is not an `SQLDatabase`, so the probe's downcast fails.
+///
+/// Every query succeeds, proving the probe reports "not reachable" because of the failed downcast
+/// rather than a failing backend.
+struct NotSQLDatabase: Database {
+
+    let context: DatabaseContext
+
+    var inTransaction: Bool { false }
+
+    func execute(
+        query: DatabaseQuery,
+        onOutput: @escaping @Sendable (any DatabaseOutput) -> Void
+    ) -> EventLoopFuture<Void> {
+        context.eventLoop.makeSucceededVoidFuture()
+    }
+
+    func execute(
+        schema: DatabaseSchema
+    ) -> EventLoopFuture<Void> {
+        context.eventLoop.makeSucceededVoidFuture()
+    }
+
+    func execute(
+        enum: DatabaseEnum
+    ) -> EventLoopFuture<Void> {
+        context.eventLoop.makeSucceededVoidFuture()
+    }
+
+    func transaction<T>(
+        _ closure: @escaping @Sendable (any Database) -> EventLoopFuture<T>
+    ) -> EventLoopFuture<T> {
+        closure(self)
+    }
+
+    func withConnection<T>(
+        _ closure: @escaping @Sendable (any Database) -> EventLoopFuture<T>
+    ) -> EventLoopFuture<T> {
+        closure(self)
+    }
+
+}