feat: ContextVM (MCP over Nostr) server with full integration

Complete CVM implementation: persistent WebSocket relay listener,
kind 25910 event subscription, MCP protocol handlers, CEP-6 announcements,
10 MCP tools, per-board hardware locks, WiFi EU regulatory fix.

Architecture:
- cvm_server.c: WS relay listener, kind 25910 subscription, MCP dispatch
- mcp_handler.c/h: 10 MCP tools (get_config, set_config, get_balance,
  wallet_send, get_sessions, get_usage, set_payout, set_metric,
  set_price, wallet_melt)
- Responses published via existing WS connection (not new TLS)
- Auth check: only owner npub accepted
- CEP-6: kinds 11316 (server), 11317 (tools), 10002 (relay list)
- WS ping/pong keepalive every 30s, 60s TLS read timeout

Critical fixes:
- WiFi country code DE (ESP-IDF defaults to CN, breaks EU APs)
- Subscription #p filter must be array not string
- Use-after-free: tags_str freed before nostr_event_to_json
- MCP responses via existing WS (ESP32 can't open multiple TLS)
- EVENT msg buffer underflow, WS frame masking, TLS write loop

Per-board hardware locks:
- Lock files in physical-router-test-automation/locks/
- lock-a/b/c, unlock-a/b/c targets in 3 Makefiles
- All hardware-touching targets require board lock

Verified on Board B via relay.primal.net:
- 282 unit tests passing (61 CVM + 60 MCP + 161 existing)
- MCP initialize roundtrip: PASS
- tools/list: PASS
- tools/call get_config: PASS
- tools/call get_balance: PASS
- tools/call set_price: PASS (write operation)
- CEP-6 announcements (11316, 11317, 10002): all accepted by relay
- WiFi STA connection (EnterSSID-2.4GHz): PASS with country code DE
- Board A WiFi confirmed hardware issue (not firmware)

1 files changed, 3 insertions, 1 deletions

diff --git a/main/CMakeLists.txt b/main/CMakeLists.txt
index 91748f2..9b0fb1c 100644
--- a/main/CMakeLists.txt
+++ b/main/CMakeLists.txt
@@ -16,8 +16,10 @@ idf_component_register(SRCS "tollgate_main.c"
                             "nip04.c"
                             "mcp_handler.c"
                             "cvm_server.c"
+                            "display.c"
+                            "font.c"
                     INCLUDE_DIRS "."
                     REQUIRES esp_wifi esp_event esp_netif nvs_flash esp_http_server
                              lwip json esp_http_client mbedtls esp-tls log spiffs
-                             nucula_lib secp256k1
+                             nucula_lib secp256k1 axs15231b qrcode
                     PRIV_REQUIRES esp-tls)