Remove prediction API endpoint and integrate into stations search

Consolidate prediction functionality by merging /api/prediction endpoint into /api/stations response. Move prediction logic from PredictionController into StationController, returning prediction data alongside station results. Replace usePrediction composable with unified useStations that returns {stations, meta, prediction}. Remove PredictionRequest, related tests, and unused Vue components (FuelFinderTest, MapTest, RecommendationTest, StationListTest). Add PredictionFull component and UpsellBanner. Extend NationalFuelPredictionService to include weekly_summary (7-day series, yesterday/today averages, cheapest/priciest days) and oil signal from price_predictions table. Update Home.vue to consume prediction from stations response. Add Plan::resolveCadenceForUser helper and configure Cashier to use custom Subscription model.

app/Models/PricePrediction.php

@@ -9,7 +9,6 @@ use Illuminate\Database\Eloquent\Attributes\Fillable;
 use Illuminate\Database\Eloquent\Builder;
 use Illuminate\Database\Eloquent\Factories\HasFactory;
 use Illuminate\Database\Eloquent\Model;
-use Illuminate\Support\Carbon;
 
 #[Fillable(['predicted_for', 'source', 'direction', 'confidence', 'reasoning', 'generated_at'])]
 class PricePrediction extends Model
@@ -39,11 +38,17 @@ class PricePrediction extends Model
      */
     public function scopeBestFirst(Builder $query): Builder
     {
-        $priority = implode(', ', array_map(
-            fn (string $v) => "'$v'",
-            [PredictionSource::LlmWithContext->value, PredictionSource::Llm->value, PredictionSource::Ewma->value],
-        ));
+        $priority = [
+            PredictionSource::LlmWithContext->value,
+            PredictionSource::Llm->value,
+            PredictionSource::Ewma->value,
+        ];
 
-        return $query->orderByRaw("FIELD(source, $priority)");
+        $cases = '';
+        foreach ($priority as $rank => $source) {
+            $cases .= " WHEN '$source' THEN $rank";
+        }
+
+        return $query->orderByRaw("CASE source$cases ELSE ".count($priority).' END');
     }
 }