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/WatchedEvents/Schemas/WatchedEventForm.php

@@ -0,0 +1,32 @@
+<?php
+
+namespace App\Filament\Resources\WatchedEvents\Schemas;
+
+use Filament\Forms\Components\DateTimePicker;
+use Filament\Forms\Components\Textarea;
+use Filament\Forms\Components\TextInput;
+use Filament\Schemas\Schema;
+
+class WatchedEventForm
+{
+    public static function configure(Schema $schema): Schema
+    {
+        return $schema->components([
+            TextInput::make('label')
+                ->required()
+                ->maxLength(128)
+                ->helperText('Short geopolitical event label, e.g. "Iran tensions Apr–May 2026".'),
+            DateTimePicker::make('starts_at')
+                ->label('Starts at')
+                ->required(),
+            DateTimePicker::make('ends_at')
+                ->label('Ends at')
+                ->required()
+                ->after('starts_at'),
+            Textarea::make('notes')
+                ->maxLength(2000)
+                ->rows(4)
+                ->columnSpanFull(),
+        ]);
+    }
+}