feat: add Filament admin panel with migrations and design spec

- Add AdminPanelProvider mounting panel at `/admin` with `is_admin` auth guard
- Add `is_admin` boolean column to users table
- Add brent_prices and price_predictions tables with appropriate indexes
- Add comprehensive admin design spec covering resources, dashboard, navigation, and build order
- Configure default panel with amber primary color and standard middleware stack
- Add compiled Filament assets (actions.js, app.css)

.claude/rules/scoring.md

@@ -32,8 +32,11 @@ Never guess — stay silent (no_signal) when signals conflict or data is insuffi
 - Weight: 15 points max
 
 ### Signal 4 — Brent crude direction (LOW WEIGHT)
-- Fetched daily from FRED API, stored in a simple `brent_prices` table
-- 5-day trend: rising ≥ 3% → mild fill_up pressure; falling ≥ 3% → mild wait
+- Read from `price_predictions` table — never query `brent_prices` directly in scoring
+- `OilPriceService::generatePrediction()` runs daily at 7am and writes the prediction
+- LLM (`source = 'llm'`) is preferred; EWMA (`source = 'ewma'`) is the fallback
+- Direction `rising` → mild fill_up pressure; `falling` → mild wait; `flat` → no signal
+- Points awarded proportionally to confidence: `(confidence / 100) * 10`
 - Weight: 10 points max
 
 ## Confidence thresholds