refactor: split oil price ingestion and prediction into separate services + commands

- BrentPriceFetcher owns ingestion (fetchFromEia / fetchFromFred, each throws on failure)
- BrentPricePredictor owns prediction and marks latest brent_prices row as generated
- oil:fetch command tries EIA, falls back to FRED, fails loudly if both fail
- oil:predict command prompts if latest price already has a prediction; --force bypasses
- add prediction_generated_at column to brent_prices
- delete OilPriceService (replaced by the two focused services)

app/Services/BrentPriceFetcher.php

@@ -0,0 +1,44 @@
+<?php
+
+namespace App\Services;
+
+use App\Models\BrentPrice;
+use App\Services\BrentPriceSources\BrentPriceFetchException;
+use App\Services\BrentPriceSources\EiaBrentPriceSource;
+use App\Services\BrentPriceSources\FredBrentPriceSource;
+
+final readonly class BrentPriceFetcher
+{
+    public function __construct(
+        private readonly EiaBrentPriceSource $eia,
+        private readonly FredBrentPriceSource $fred,
+    ) {}
+
+    /**
+     * Fetch from EIA and persist. Throws on failure.
+     */
+    public function fetchFromEia(): void
+    {
+        $rows = $this->eia->fetch();
+
+        if ($rows === null) {
+            throw new BrentPriceFetchException('EIA fetch returned no data');
+        }
+
+        BrentPrice::upsert($rows, ['date'], ['price_usd']);
+    }
+
+    /**
+     * Fetch from FRED and persist. Throws on failure.
+     */
+    public function fetchFromFred(): void
+    {
+        $rows = $this->fred->fetch();
+
+        if ($rows === null) {
+            throw new BrentPriceFetchException('FRED fetch returned no data');
+        }
+
+        BrentPrice::upsert($rows, ['date'], ['price_usd']);
+    }
+}