Remove Cashu Access Token (CAT) system entirely (v0.52.3)

- Delete pkg/cashu/ package (BDHKE, issuer, verifier, keyset, token)
- Delete pkg/interfaces/cashu/ interface definitions
- Delete pkg/bunker/acl_adapter.go CAT authorization checker
- Delete app/handle-cashu.go HTTP handlers for mint endpoints
- Delete docs/NIP-XX-CASHU-ACCESS-TOKENS.md specification
- Remove Cashu config fields from app/config/config.go
- Remove CashuIssuer/CashuVerifier from app/server.go
- Remove CAT initialization and NRC Cashu verifier from app/main.go
- Remove token extraction from app/handle-websocket.go
- Remove CAT permission checks from app/handle-event.go
- Remove CashuEnabled from bunker info response
- Remove UseCashu field from NRC connections
- Remove AuthModeCAT from NRC protocol
- Remove CAT UI from BunkerView.svelte and RelayConnectView.svelte
- Remove cashu-client.js from web UI
- Add missing bunker worker stores to stores.js

Files modified:
- app/config/config.go: Removed Cashu config fields
- app/server.go: Removed Cashu issuer/verifier
- app/main.go: Removed Cashu initialization
- app/handle-*.go: Removed CAT checks and handlers
- app/listener.go: Removed cashuToken field
- pkg/database/nrc.go: Removed UseCashu field
- pkg/protocol/nrc/: Removed CAT auth mode and handling
- pkg/event/authorization/: Removed CAT import
- app/web/src/: Removed CAT UI components and logic
- main.go: Removed CAT help text

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

app/handle-bunker.go

@@ -18,7 +18,6 @@ type BunkerInfoResponse struct {
 	RelayNpub    string `json:"relay_npub"`     // Relay's npub
 	RelayPubkey  string `json:"relay_pubkey"`   // Relay's hex pubkey
 	ACLMode      string `json:"acl_mode"`       // Current ACL mode
-	CashuEnabled bool   `json:"cashu_enabled"`  // Whether CAT is required
 	Available    bool   `json:"available"`      // Whether bunker is available
 }
 
@@ -63,19 +62,15 @@ func (s *Server) handleBunkerInfo(w http.ResponseWriter, r *http.Request) {
 	wsURL := strings.Replace(serviceURL, "https://", "wss://", 1)
 	wsURL = strings.Replace(wsURL, "http://", "ws://", 1)
 
-	// Check if Cashu is enabled
-	cashuEnabled := s.CashuIssuer != nil
-
 	// Bunker is available when ACL mode is not "none"
 	available := s.Config.ACLMode != "none"
 
 	resp := BunkerInfoResponse{
-		RelayURL:     wsURL,
-		RelayNpub:    relayNpub,
-		RelayPubkey:  relayPubkeyHex,
-		ACLMode:      s.Config.ACLMode,
-		CashuEnabled: cashuEnabled,
-		Available:    available,
+		RelayURL:    wsURL,
+		RelayNpub:   relayNpub,
+		RelayPubkey: relayPubkeyHex,
+		ACLMode:     s.Config.ACLMode,
+		Available:   available,
 	}
 
 	w.Header().Set("Content-Type", "application/json")