security+reliability: remove public decrypt endpoint, add panic recovery for goroutines

Security:
- Remove /api/crypto/decrypt from public routes. The endpoint allowed
  anyone to decrypt ciphertext without authentication. Internal callers
  (exchange/model handlers) use the service directly and are behind auth.

Reliability:
- Add safe.Go / safe.GoNamed panic recovery wrapper (safe/go.go).
  Previously 31 goroutines had zero recover() calls — a single panic
  in any trader goroutine would crash the entire process.
- Apply safe.GoNamed to all trader launch paths:
  - StartAll, RestoreRunning, LoadSingleTrader auto-start
  - API handler start/restart endpoints
- Panics are now logged with full stack traces instead of crashing.

api/server.go

@@ -126,10 +126,11 @@ func (s *Server) setupRoutes() {
 		api.POST("/wallet/validate", s.handleWalletValidate)
 		api.POST("/wallet/generate", s.handleWalletGenerate)
 
-		// Crypto related endpoints (no authentication required, not exposed to bot)
+		// Crypto public key & config (needed by frontend before login for transport encryption)
 		api.GET("/crypto/config", s.cryptoHandler.HandleGetCryptoConfig)
 		api.GET("/crypto/public-key", s.cryptoHandler.HandleGetPublicKey)
-		api.POST("/crypto/decrypt", s.cryptoHandler.HandleDecryptSensitiveData)
+		// NOTE: /crypto/decrypt moved behind auth — the public endpoint was a security risk
+		// (allowed anyone to decrypt captured ciphertext without authentication)
 
 		// Public competition data (no authentication required)
 		s.route(api, "GET", "/traders", "Public trader list", s.handlePublicTraderList)