feat: implement symbol-specific position sizing for multi-asset trading

- Extended MarketConfig with optional positionSize and leverage fields
- Configured ETH-PERP at  @ 1x leverage for minimal-risk data collection
- Created getPositionSizeForSymbol() helper function in config/trading.ts
- Integrated symbol-specific sizing into execute endpoint
- Added comprehensive guide in docs/guides/SYMBOL_SPECIFIC_SIZING.md

Purpose: Enable ETH trading for faster signal quality data collection
         while preserving SOL's profit-generation sizing (0 @ 10x)

Next: Create ETH alert in TradingView and restart bot

config/trading.ts

@@ -54,6 +54,9 @@ export interface MarketConfig {
   pythPriceFeedId: string
   minOrderSize: number
   tickSize: number
+  // Position sizing overrides (optional)
+  positionSize?: number
+  leverage?: number
 }
 
 // Default configuration for 5-minute scalping with $1000 capital and 10x leverage
@@ -108,6 +111,7 @@ export const SUPPORTED_MARKETS: Record<string, MarketConfig> = {
     pythPriceFeedId: '0xef0d8b6fda2ceba41da15d4095d1da392a0d2f8ed0c6c7bc0f4cfac8c280b56d',
     minOrderSize: 0.1, // 0.1 SOL minimum
     tickSize: 0.0001,
+    // Use default config values (positionSize: 50, leverage: 10)
   },
   'BTC-PERP': {
     symbol: 'BTC-PERP',
@@ -115,6 +119,7 @@ export const SUPPORTED_MARKETS: Record<string, MarketConfig> = {
     pythPriceFeedId: '0xe62df6c8b4a85fe1a67db44dc12de5db330f7ac66b72dc658afedf0f4a415b43',
     minOrderSize: 0.001, // 0.001 BTC minimum
     tickSize: 0.01,
+    // Use default config values
   },
   'ETH-PERP': {
     symbol: 'ETH-PERP',
@@ -122,6 +127,9 @@ export const SUPPORTED_MARKETS: Record<string, MarketConfig> = {
     pythPriceFeedId: '0xff61491a931112ddf1bd8147cd1b641375f79f5825126d665480874634fd0ace',
     minOrderSize: 0.01, // 0.01 ETH minimum
     tickSize: 0.01,
+    // DATA COLLECTION MODE: Minimal risk
+    positionSize: 1,  // $1 USD base capital only
+    leverage: 1,      // 1x leverage = $1 position size total
   },
 }
 
@@ -147,6 +155,16 @@ export function getMarketConfig(symbol: string): MarketConfig {
   return config
 }
 
+// Get position size for specific symbol (with market-specific overrides)
+export function getPositionSizeForSymbol(symbol: string, baseConfig: TradingConfig): { size: number; leverage: number } {
+  const marketConfig = getMarketConfig(symbol)
+  
+  return {
+    size: marketConfig.positionSize ?? baseConfig.positionSize,
+    leverage: marketConfig.leverage ?? baseConfig.leverage
+  }
+}
+
 // Validate trading configuration
 export function validateTradingConfig(config: TradingConfig): void {
   if (config.positionSize <= 0) {