refactor(services): split driver infrastructure out of Services into Support

Services/Integrations/ExchangeRate/ and Services/Pdf/ were both mostly Support-shaped: interfaces, abstract classes, static factories, concrete adapter drivers, DTOs, and exceptions — infrastructure that doesn't carry business logic. They only each had one real DI-injected service mixed in.

This commit applies the same Services=DI-business-logic / Support=stateless-plumbing rule we've been using throughout the reorg:

**Moved to Support/Integrations/ExchangeRate/** (7 files): ExchangeRateDriver (abstract), ExchangeRateDriverFactory (static), ExchangeRateException, and the four concrete drivers (CurrencyConverter, CurrencyFreak, CurrencyLayer, OpenExchangeRate). These are HTTP adapters over third-party currency APIs — same shape as the Hashids library wrapper classes already in Support.

**Moved to Support/Pdf/** (6 files, merging with existing Pdf utilities): PdfDriver (interface), PdfDriverFactory (static), PdfService (static facade), GotenbergPdfDriver, GotenbergPdfResponse (DTO), ResponseStream (interface). The Support/Pdf/ dir now contains the full PDF rendering subsystem — drivers + sanitizer + template/image utilities.

**Promoted to Services/ root** (the real DI services): ExchangeRateProviderService (CRUD for ExchangeRateProvider model) and FontService (font package install/download orchestration). Both are proper DI services — instance methods, model writes, HTTP side effects.

Services/Integrations/ and Services/Pdf/ are now empty and deleted. Services/ holds only DI-injected classes; Support/ holds all the plumbing.

17 files renamed (git detects 90-99% similarity), 4 consumer files updated (DriverRegistryProvider, PdfServiceProvider, ExchangeRateProviderController, FontController, GeneratesPdfTrait, test). 350 tests pass, Pint clean.

app/Support/Integrations/ExchangeRate/ExchangeRateDriverFactory.php

@@ -0,0 +1,79 @@
+<?php
+
+namespace App\Support\Integrations\ExchangeRate;
+
+use InvalidArgumentException;
+use InvoiceShelf\Modules\Registry;
+
+class ExchangeRateDriverFactory
+{
+    /**
+     * Built-in driver fallback map.
+     *
+     * Kept as a backstop so that direct calls to register() (without going through
+     * the module Registry) continue to work. Built-in drivers are also registered
+     * via the Registry by DriverRegistryProvider — that registration is the
+     * canonical source for driver metadata (label, website, config_fields).
+     *
+     * @var array<string, class-string<ExchangeRateDriver>>
+     */
+    protected static array $drivers = [
+        'currency_freak' => CurrencyFreakDriver::class,
+        'currency_layer' => CurrencyLayerDriver::class,
+        'open_exchange_rate' => OpenExchangeRateDriver::class,
+        'currency_converter' => CurrencyConverterDriver::class,
+    ];
+
+    /**
+     * Register a custom exchange rate driver directly with the factory.
+     *
+     * Modules should prefer Registry::registerExchangeRateDriver() instead, which
+     * carries metadata (label, website, config_fields) the frontend needs to render
+     * a configuration form for the driver.
+     */
+    public static function register(string $name, string $driverClass): void
+    {
+        static::$drivers[$name] = $driverClass;
+    }
+
+    public static function make(string $driver, string $apiKey, array $config = []): ExchangeRateDriver
+    {
+        $class = static::resolveDriverClass($driver);
+
+        if (! $class) {
+            throw new InvalidArgumentException("Unknown exchange rate driver: {$driver}");
+        }
+
+        return new $class($apiKey, $config);
+    }
+
+    /**
+     * Get all known driver names — both built-in/factory-registered and Registry-registered.
+     *
+     * @return array<int, string>
+     */
+    public static function availableDrivers(): array
+    {
+        $local = array_keys(static::$drivers);
+        $registry = array_keys(Registry::allDrivers('exchange_rate'));
+
+        return array_values(array_unique(array_merge($local, $registry)));
+    }
+
+    /**
+     * Resolve a driver name to its concrete class.
+     *
+     * Checks the local $drivers map first (built-ins and factory::register() calls),
+     * then falls back to the module Registry.
+     */
+    protected static function resolveDriverClass(string $driver): ?string
+    {
+        if (isset(static::$drivers[$driver])) {
+            return static::$drivers[$driver];
+        }
+
+        $meta = Registry::driverMeta('exchange_rate', $driver);
+
+        return $meta['class'] ?? null;
+    }
+}