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/Repositories/ExampleRepository.swift

@@ -0,0 +1,63 @@
+import FluentKit
+import Foundation
+import HummingbirdFluent
+
+/// A `Sendable` snapshot of an ``ExampleRecord``, safe to return across concurrency boundaries.
+///
+/// Repositories return these value-type snapshots rather than FluentKit models, which are mutable reference
+/// types that must not escape the database's execution context.
+public struct Example: Sendable, Equatable {
+
+    // MARK: Properties
+
+    /// The record's primary key, or `nil` if it has never been saved.
+    public let id: UUID?
+    /// The record's name.
+    public let name: String
+
+}
+
+/// Reads and writes ``ExampleRecord`` rows through the default database.
+///
+/// This is the shape every real repository takes: it holds the `Sendable` `Fluent` service, resolves the
+/// default database per call, and maps FluentKit models to `Sendable` snapshots before returning — so no
+/// model ever escapes across an async boundary. It is reference scaffolding paired with ``ExampleRecord``;
+/// replace it with the first real repository once a domain model is defined.
+public struct ExampleRepository: Sendable {
+
+    // MARK: Properties
+
+    /// The service providing the default database the repository reads and writes through.
+    private let fluent: Fluent
+
+    // MARK: Initializers
+
+    /// Creates a repository backed by the given `Fluent` service.
+    /// - Parameter fluent: the service whose default database the repository operates on.
+    public init(fluent: Fluent) {
+        self.fluent = fluent
+    }
+
+    // MARK: Methods
+
+    /// Inserts a record with the given name.
+    /// - Parameter name: the name of the record to insert.
+    /// - Returns: a `Sendable` snapshot of the inserted record, including its assigned identifier.
+    public func create(name: String) async throws -> Example {
+        let record = ExampleRecord(name: name)
+
+        try await record.save(on: fluent.db())
+
+        return Example(id: record.id, name: record.name)
+    }
+
+    /// Fetches every record, ordered by name.
+    /// - Returns: a `Sendable` snapshot of each record, sorted by name.
+    public func all() async throws -> [Example] {
+        try await ExampleRecord.query(on: fluent.db())
+            .sort(\.$name)
+            .all()
+            .map { Example(id: $0.id, name: $0.name) }
+    }
+
+}