critical: Fix exit order token sizing - TP/SL now use exact position size

BUG #92: Exit orders (TP1, TP2, SL) had different token sizes than position
- Position: 142.91 SOL but TP1=140.87 SOL, SL=147.03 SOL (WRONG)
- Root cause: usdToBase() calculated tokens as USD/price per order
- Each exit order price produced different token amounts

FIX: Pass actual token count via positionSizeTokens parameter
- Added positionSizeTokens to PlaceExitOrdersOptions interface
- Added tokensToBase() helper (tokens * 1e9 directly)
- All exit sections now use token-based calculation when available

Files updated to pass positionSizeTokens:
- app/api/trading/execute/route.ts: openResult.fillSize
- lib/trading/smart-entry-timer.ts: openResult.fillSize
- lib/trading/sync-helper.ts: Math.abs(driftPos.size)
- lib/trading/position-manager.ts: Math.abs(position.size) + fetch patterns
- lib/startup/init-position-manager.ts: Math.abs(position.size)
- lib/health/position-manager-health.ts: Drift position fetch + token size

Result: When position = X tokens, ALL exit orders close portions of X tokens
- TP1: X * tp1SizePercent / 100 tokens
- TP2: remaining * tp2SizePercent / 100 tokens
- SL: X tokens (full position)

Backward compatible: Falls back to USD calculation if positionSizeTokens not provided

lib/health/position-manager-health.ts

@@ -128,9 +128,28 @@ async function ensureExitOrdersForTrade(
 
     const { placeExitOrders } = await import('../drift/orders')
 
+    // Fetch current position size in tokens for accurate order sizing
+    let positionSizeTokens: number | undefined
+    try {
+      const { getDriftService } = await import('../drift/client')
+      const { getMarketConfig } = await import('../../config/trading')
+      const driftService = getDriftService()
+      if (driftService && (driftService as any).isInitialized) {
+        const marketConfig = getMarketConfig(trade.symbol)
+        const position = await driftService.getPosition(marketConfig.driftMarketIndex)
+        if (position && Math.abs(position.size) > 0.01) {
+          positionSizeTokens = Math.abs(position.size)
+          console.log(`📊 Position size for health monitor orders: ${positionSizeTokens.toFixed(4)} tokens`)
+        }
+      }
+    } catch (posError) {
+      console.warn('⚠️ Could not fetch position for health monitor token size, using USD fallback')
+    }
+
     const placeResult = await placeExitOrders({
       symbol: trade.symbol,
       positionSizeUSD,
+      positionSizeTokens,
       entryPrice: trade.entryPrice,
       tp1Price,
       tp2Price,