fix: redeemer executes via Gnosis Safe proxy wallet (same as MM bot)

redeemer.js was calling redeemPositions() directly from the EOA private
key wallet. This is wrong for two reasons:
1. Conditional tokens are held in config.proxyWallet (Gnosis Safe), not
   in the EOA — so the EOA has nothing to redeem
2. No maxPriorityFeePerGas was set, causing Polygon's "gas tip below
   minimum" error (1.5 Gwei sent, 25 Gwei required)

Fix: replace the direct contract call with execSafeCall() (exported from
ctf.js), which is identical to the MM bot's redemption pattern:
- encodes calldata and executes via Safe.execTransaction()
- signed by the EOA, but msg.sender on-chain = proxy wallet
- enforces 30 Gwei minimum priority fee for Polygon
- retries up to 3x on transient RPC errors

Also remove the now-unused NEG_RISK_CTF_ADDRESS local constant
(CTF_ADDRESS and USDC_ADDRESS imported from ctf.js).

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

src/services/ctf.js

@@ -105,7 +105,7 @@ let _txQueue = Promise.resolve();
  * Calls are serialized via an internal queue so nonces never collide.
  * Retries up to MAX_RETRIES times on transient errors.
  */
-function execSafeCall(to, data, description = '') {
+export function execSafeCall(to, data, description = '') {
     // Enqueue: this call will only start after the previous one resolves/rejects
     const result = _txQueue.then(() => _doExecSafeCall(to, data, description));
     // Don't let a failure poison the queue for subsequent calls