Phase 7: MCP handler (25 tests), NIP-04 encrypt/decrypt (15 tests), CVM server skeleton

- mcp_handler.c/h: 4 tools (get_config, set_config, get_balance, wallet_send)
- nip04.c/h: AES-256-CBC + ECDH with 0x02 compressed pubkey prefix
  - Fixed IV copy bug: mbedTLS AES-CBC modifies IV in-place
  - Base64 encode/decode for ciphertext transport
  - PKCS7 padding
- cvm_server.c/h: Nostr DM listener with FreeRTOS task
- config: cvm_enabled, cvm_relays fields
- 156 total tests passing across 10 test binaries

1 files changed, 10 insertions, 0 deletions

diff --git a/main/cvm_server.h b/main/cvm_server.h
new file mode 100644
index 0000000..d336514
--- /dev/null
+++ b/main/cvm_server.h
@@ -0,0 +1,10 @@
+#ifndef CVM_SERVER_H
+#define CVM_SERVER_H
+
+#include "esp_err.h"
+
+esp_err_t cvm_server_init(void);
+void cvm_server_start(void);
+void cvm_server_stop(void);
+
+#endif