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/Package.swift

@@ -0,0 +1,67 @@
+// swift-tools-version: 6.3
+
+import PackageDescription
+
+let package = Package(
+    name: "Persistence",
+    platforms: [
+        .macOS(.v15),
+    ],
+    products: [
+        .library(
+            name: "Persistence",
+            targets: [
+                "Persistence"
+            ]
+        )
+    ],
+    dependencies: [
+        .package(
+            url: "https://github.com/hummingbird-project/hummingbird-fluent.git",
+            from: "2.0.0"
+        ),
+        .package(
+            url: "https://github.com/vapor/fluent-mysql-driver.git",
+            from: "4.8.0"
+        ),
+        .package(
+            url: "https://github.com/vapor/fluent-sqlite-driver.git",
+            from: "4.9.0"
+        ),
+        .package(
+            url: "https://github.com/vapor/sql-kit.git",
+            from: "3.36.0"
+        ),
+    ],
+    targets: [
+        .target(
+            name: "Persistence",
+            dependencies: [
+                .product(
+                    name: "HummingbirdFluent",
+                    package: "hummingbird-fluent"
+                ),
+                .product(
+                    name: "FluentMySQLDriver",
+                    package: "fluent-mysql-driver"
+                ),
+                .product(
+                    name: "FluentSQLiteDriver",
+                    package: "fluent-sqlite-driver"
+                ),
+                .product(
+                    name: "SQLKit",
+                    package: "sql-kit"
+                ),
+            ],
+            path: "Sources"
+        ),
+        .testTarget(
+            name: "PersistenceTests",
+            dependencies: [
+                .byName(name: "Persistence")
+            ],
+            path: "Tests"
+        ),
+    ]
+)