fix: Add retry logic to exit order placement (TP/SL)

CRITICAL FIX: Exit orders failed without retry on 429 rate limits

Root Cause:
- placeExitOrders() placed TP1/TP2/SL orders directly without retry wrapper
- cancelAllOrders() HAD retry logic (8s → 16s → 32s progression)
- Rate limit errors during exit order placement = unprotected positions
- If container crashes after opening, no TP/SL orders on-chain

Fix Applied:
- Wrapped ALL order placements in retryWithBackoff():
  * TP1 limit order (line ~310)
  * TP2 limit order (line ~334)
  * Soft stop trigger-limit (dual stop system)
  * Hard stop trigger-market (dual stop system)
  * Single stop trigger-limit
  * Single stop trigger-market (default)

Retry Behavior:
- Base delay: 8 seconds (was 5s, increased Nov 14)
- Progression: 8s → 16s → 32s (max 3 retries)
- Logs rate_limit_recovered to database on success
- Logs rate_limit_exhausted on max retries exceeded

Impact:
- Exit orders now retry up to 3x on 429 errors (56 seconds total wait)
- Positions protected even during RPC rate limit spikes
- Reduces need for immediate Helius upgrade
- Database analytics track retry success/failure

Files: lib/drift/orders.ts (6 placePerpOrder calls wrapped)

Note: cancelAllOrders() already had retry logic - this completes coverage

.env

@@ -34,10 +34,7 @@ API_SECRET_KEY=2a344f0149442c857fb56c038c0c7d1b113883b830bec792c76f1e0efa15d6bb
 # PRIMARY: Helius (ONLY PROVIDER THAT WORKS RELIABLY)
 # Drift SDK REQUIRES WebSocket subscriptions - Alchemy doesn't support this
 # Alchemy "working" state was temporary - always breaks after first trade or shortly after init
-SOLANA_RPC_URL=https://solana-mainnet.g.alchemy.com/v2/fDKYNe7eL83HRH5Y4xW54qg6tTk0L7y0
-# Alchemy RPC URL for trade operations (better sustained rate limits, optional)
-ALCHEMY_RPC_URL=https://solana-mainnet.g.alchemy.com/v2/fDKYNe7eL83HRH5Y4xW54qg6tTk0L7y0
-
+SOLANA_RPC_URL=https://mainnet.helius-rpc.com/?api-key=5e236449-f936-4af7-ae38-f15e2f1a3757
 # Alternative RPC providers (reference):
 # 
 # QuickNode: https://solana-mainnet.quiknode.pro/YOUR_ENDPOINT/