v0.3.4 - Implement secure relay private key storage

- Add relay_seckey table for secure private key storage
- Implement store_relay_private_key() and get_relay_private_key() functions
- Remove relay private key from public configuration events (kind 33334)
- Update first-time startup sequence to store keys securely after DB init
- Add proper validation and error handling for private key operations
- Fix timing issue where private key storage was attempted before DB initialization
- Security improvement: relay private keys no longer exposed in public events

src/config.h

@@ -79,4 +79,9 @@ int apply_runtime_config_handlers(const cJSON* old_event, const cJSON* new_event
 char** find_existing_db_files(void);
 char* extract_pubkey_from_filename(const char* filename);
 
+// Secure relay private key storage functions
+int store_relay_private_key(const char* relay_privkey_hex);
+char* get_relay_private_key(void);
+const char* get_temp_relay_private_key(void);  // For first-time startup only
+
 #endif /* CONFIG_H */