feat(admin): add Filament resources for the forecasting stack

Adds three resources under a new "Forecasting" navigation group: a full-CRUD
WatchedEventResource for the Layer 5 volatility detector, plus read-only
WeeklyForecastResource and BacktestResource so the ridge model output and
its calibration can be inspected without SQL.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

database/factories/WeeklyForecastFactory.php

@@ -0,0 +1,24 @@
+<?php
+
+namespace Database\Factories;
+
+use App\Models\WeeklyForecast;
+use Illuminate\Database\Eloquent\Factories\Factory;
+
+/** @extends Factory<WeeklyForecast> */
+class WeeklyForecastFactory extends Factory
+{
+    public function definition(): array
+    {
+        return [
+            'forecast_for' => now()->startOfWeek()->toDateString(),
+            'model_version' => 'ridge-'.fake()->unique()->bothify('????????'),
+            'direction' => fake()->randomElement(['rising', 'falling', 'flat']),
+            'magnitude_pence' => fake()->numberBetween(-300, 300),
+            'ridge_confidence' => fake()->numberBetween(20, 90),
+            'flagged_duty_change' => false,
+            'reasoning' => fake()->paragraph(),
+            'generated_at' => now(),
+        ];
+    }
+}