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/Sources/Internal/Migrations/CreateExampleRecord.swift

@@ -0,0 +1,28 @@
+import FluentKit
+
+/// Creates and drops the `example_records` table backing ``ExampleRecord``.
+///
+/// Reference scaffolding paired with ``ExampleRecord``; replace it with the first real migration once a
+/// domain model is defined. Migrations are append-only in production — add a new migration to alter the
+/// schema rather than editing one that has already run.
+struct CreateExampleRecord: AsyncMigration {
+
+    // MARK: Methods
+
+    /// Creates the `example_records` table with an `id` primary key and a required `name` column.
+    /// - Parameter database: the database the schema change is applied to.
+    func prepare(on database: Database) async throws {
+        try await database.schema(ExampleRecord.schema)
+            .id()
+            .field("name", .string, .required)
+            .create()
+    }
+
+    /// Drops the `example_records` table, reverting ``prepare(on:)``.
+    /// - Parameter database: the database the schema change is applied to.
+    func revert(on database: Database) async throws {
+        try await database.schema(ExampleRecord.schema)
+            .delete()
+    }
+
+}