Phase 3: Nostr identity derivation + wifistr service discovery

- Add identity.c/h: HMAC-SHA512 derivation from nsec → npub, STA/AP MAC, SSID, AP IP
- Add nostr_event.c/h: NIP-01 event serialization + Schnorr signing (BIP-340)
- Add geohash.c/h: lat/lon to geohash encoding
- Add wifistr.c/h: kind 38787 event builder + WebSocket publish to Nostr relays
- Update config.c/h: nsec-based identity, Nostr relay/geo config, remove static SSID/IP
- Replace custom mbedTLS wallet with nucula library (libsecp256k1)
- Remove wallet.c/h, wallet_persist.c/h (replaced by nucula_lib component)
- Verified on Board A: derived SSID, captive portal, payment, wallet, wifistr publish

1 files changed, 17 insertions, 0 deletions

diff --git a/components/nucula_lib/CMakeLists.txt b/components/nucula_lib/CMakeLists.txt
new file mode 100644
index 0000000..ea1605e
--- /dev/null
+++ b/components/nucula_lib/CMakeLists.txt
@@ -0,0 +1,17 @@
+set(NUCULA_SRC ${CMAKE_CURRENT_SOURCE_DIR}/../../nucula_src/main)
+
+idf_component_register(
+    SRCS "nucula_wallet.cpp"
+         "${NUCULA_SRC}/crypto.c"
+         "${NUCULA_SRC}/wallet.cpp"
+         "${NUCULA_SRC}/cashu_json.cpp"
+         "${NUCULA_SRC}/nut10.cpp"
+         "${NUCULA_SRC}/hex.c"
+         "${NUCULA_SRC}/http.c"
+    INCLUDE_DIRS "."
+                 "${NUCULA_SRC}"
+    REQUIRES secp256k1
+    PRIV_REQUIRES log mbedtls nvs_flash esp_http_client json
+)
+
+target_compile_options(${COMPONENT_LIB} PRIVATE -Wno-unused-function)