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>

app/Filament/Resources/Backtests/Schemas/BacktestInfolist.php

@@ -0,0 +1,89 @@
+<?php
+
+namespace App\Filament\Resources\Backtests\Schemas;
+
+use App\Models\Backtest;
+use Filament\Infolists\Components\IconEntry;
+use Filament\Infolists\Components\KeyValueEntry;
+use Filament\Infolists\Components\TextEntry;
+use Filament\Schemas\Components\Section;
+use Filament\Schemas\Schema;
+
+class BacktestInfolist
+{
+    public static function configure(Schema $schema): Schema
+    {
+        return $schema->components([
+            Section::make('Run')->columns(3)->schema([
+                TextEntry::make('model_version')->columnSpanFull(),
+                TextEntry::make('directional_accuracy')
+                    ->label('Accuracy')
+                    ->state(fn (Backtest $record): string => $record->directional_accuracy === null
+                        ? '—'
+                        : round((float) $record->directional_accuracy, 1).'%'),
+                TextEntry::make('mae_pence')
+                    ->label('MAE')
+                    ->state(fn (Backtest $record): string => $record->mae_pence === null
+                        ? '—'
+                        : number_format((float) $record->mae_pence, 2).'p'),
+                IconEntry::make('leak_suspected')
+                    ->label('Leak suspected')
+                    ->boolean()
+                    ->trueColor('danger'),
+                TextEntry::make('train_start')->date('d M Y'),
+                TextEntry::make('train_end')->date('d M Y'),
+                TextEntry::make('eval_start')->date('d M Y'),
+                TextEntry::make('eval_end')->date('d M Y'),
+                TextEntry::make('ran_at')->dateTime('d M Y H:i'),
+            ]),
+            Section::make('Calibration table')
+                ->description('Empirical hit rate per magnitude bin from the eval window.')
+                ->schema([
+                    KeyValueEntry::make('calibration_table')
+                        ->hiddenLabel()
+                        ->keyLabel('Magnitude bin')
+                        ->valueLabel('Empirical hit rate')
+                        ->state(fn (Backtest $record): array => collect($record->calibration_table ?? [])
+                            ->mapWithKeys(fn ($value, $key) => [$key => round((float) $value * 100, 1).'%'])
+                            ->all())
+                        ->columnSpanFull(),
+                ]),
+            Section::make('Feature spec')->schema([
+                KeyValueEntry::make('features_json')
+                    ->hiddenLabel()
+                    ->state(fn (Backtest $record): array => self::flattenForKeyValue($record->features_json))
+                    ->columnSpanFull(),
+            ]),
+            Section::make('Coefficients')
+                ->visible(fn (Backtest $record) => $record->coefficients_json !== null)
+                ->collapsed()
+                ->schema([
+                    TextEntry::make('coefficients_json')
+                        ->hiddenLabel()
+                        ->state(fn (Backtest $record): string => json_encode(
+                            $record->coefficients_json,
+                            JSON_PRETTY_PRINT | JSON_UNESCAPED_SLASHES
+                        ) ?: '')
+                        ->columnSpanFull(),
+                ]),
+        ]);
+    }
+
+    /**
+     * KeyValueEntry expects a flat string-keyed map, so collapse nested arrays
+     * into JSON strings rather than dropping them.
+     *
+     * @param  array<string, mixed>|null  $features
+     * @return array<string, string>
+     */
+    protected static function flattenForKeyValue(?array $features): array
+    {
+        return collect($features ?? [])
+            ->mapWithKeys(fn ($value, $key) => [
+                (string) $key => is_scalar($value)
+                    ? (string) $value
+                    : (json_encode($value, JSON_UNESCAPED_SLASHES) ?: ''),
+            ])
+            ->all();
+    }
+}