feat: local Nostr relay with relay selection, sync, and integration tests

Local Nostr relay (NIP-01) on port 4869 with LittleFS 4MB storage.
All events published locally first, then synced to public relays via REQ-diff.
Relay selection via NIP-11 HTTP probing with NIP-77 scoring and auto-failover.

Components:
- wisp_relay: 16-file local relay (ws_server, storage_engine, sub_manager,
  broadcaster, relay_validator, router, handlers, rate_limiter, nip11,
  deletion, flash_monitor, relay_types)
- esp_littlefs: LittleFS VFS integration (git submodule)
- negentropy: for future NIP-77 binary sync (git submodule)

New source files:
- local_relay.c/h: thin wrapper for relay init/start/publish
- relay_selector.c/h: NIP-11 probe + scoring + auto-failover
- sync_manager.c/h: REQ-diff sync (primary 30min, fallback 6h)

Bug fixes:
- config.c: use-after-free (cJSON_Delete before seed_relays/sync parsing)
- local_relay: moved init to app_main for boot-time start (not gated on STA IP)

Flash layout: 4MB LittleFS partition at 0x500000 for relay_store

Test results (Board B, live hardware):
- Smoke: ping + HTTP 4869 + NIP-11: PASS
- NIP-11 info document: 10/11 PASS
- WS pub/sub (connect, REQ/EOSE, EVENT/OK, CLOSE, concurrent): 6/6 PASS
- Unit tests (relay_validator + relay_selector): 13/13 PASS

Hardware test make targets in physical-router-test-automation/:
- make relay-build, relay-flash-b, relay-test-smoke/nip11/pubsub/sync/full

1 files changed, 18 insertions, 0 deletions

diff --git a/main/tollgate_main.c b/main/tollgate_main.c
index ad5211a..4741765 100644
--- a/main/tollgate_main.c
+++ b/main/tollgate_main.c
@@ -24,6 +24,9 @@
 #include "lightning_payout.h"
 #include "cvm_server.h"
 #include "display.h"
+#include "local_relay.h"
+#include "relay_selector.h"
+#include "sync_manager.h"
 
 #define MAX_STA_RETRY 5
 static const char *TAG = "tollgate_main";
@@ -38,6 +41,9 @@ static bool s_services_running = false;
 static SemaphoreHandle_t s_services_mutex = NULL;
 static char s_ap_ip_str[16] = "10.0.0.1";
 
+static relay_selector_t s_relay_selector;
+static sync_manager_t s_sync_manager;
+
 static void start_services(void);
 static void stop_services(void);
 
@@ -159,6 +165,12 @@ static void start_services(void)
     captive_portal_start(cfg->ap_ip_str);
     tollgate_api_start();
 
+    relay_selector_init(&s_relay_selector);
+    relay_selector_seed_from_config(&s_relay_selector);
+
+    sync_manager_init(&s_sync_manager, &s_relay_selector);
+    sync_manager_start(&s_sync_manager);
+
     xTaskCreate(publish_wifistr_task, "wifistr_init", 16384, NULL, 3, NULL);
 
     const tollgate_config_t *cfg2 = tollgate_config_get();
@@ -189,6 +201,9 @@ static void stop_services(void)
     tollgate_api_stop();
     dns_server_stop();
     cvm_server_stop();
+    sync_manager_stop(&s_sync_manager);
+    local_relay_stop();
+    relay_selector_destroy(&s_relay_selector);
     firewall_revoke_all();
     s_services_running = false;
     if (s_services_mutex) xSemaphoreGive(s_services_mutex);
@@ -311,6 +326,9 @@ void app_main(void)
 
     ESP_ERROR_CHECK(esp_wifi_start());
 
+    local_relay_init();
+    local_relay_start();
+
     ESP_LOGI(TAG, "WiFi AP+STA started, waiting for connection...");
 
     if (tollgate_config_get_wifi(&(wifi_config_t){0}) != ESP_OK) {