fix: critical bugs, type corrections, RTDS race condition, and comprehensive test coverage

- Fix UpdateBalanceAllowance response not being unmarshaled (pkg/clob)
- Fix SignatureType enum collision: SignatureMagic and SignatureProxy both had value 1 (pkg/auth)
- Fix salt validation inconsistency: generation limited to 53 bits but validation allowed 63 bits (pkg/clob)
- Fix PriceHistoryPoint.Price type from string to float64 to match API response (pkg/clob/clobtypes)
- Fix RTDS subscribe race condition: subscribeRaw now waits for WebSocket connection before sending
- Add comprehensive tests for pkg/data (9.4% → 63.8%), pkg/ctf (11.6% → 71.1%),
  pkg/clob/ws (33.8% → 63.6%), pkg/rtds (35.0% → 62.1%), pkg/clob/rfq (38.5% → 100%),
  pkg/bridge (42.0% → 67.0%)

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: dongowu

pkg/auth/auth.go

@@ -71,10 +71,9 @@ type SignatureType int
 
 const (
 	// SignatureEOA indicates a standard Externally Owned Account (EOA).
-	SignatureEOA SignatureType = iota
-	// SignatureMagic indicates a signature from a Magic.link wallet.
-	SignatureMagic
+	SignatureEOA SignatureType = 0
 	// SignatureProxy indicates a signature from a Polymarket Proxy wallet.
+	// Magic.link wallets use the same proxy factory, so SignatureProxy covers both.
 	SignatureProxy SignatureType = 1
 	// SignatureGnosisSafe indicates a signature from a Gnosis Safe multisig.
 	SignatureGnosisSafe SignatureType = 2