Add WiFi reconnection retry logic to recover from unreliable WiFi

- Implement periodic WiFi reconnection attempts when stuck in AP mode
- Add WIFI_RECONNECT_INTERVAL_MS config (default 60s) for configurable retry frequency
- Prevent data loss by automatically attempting to switch back to STA mode
- Maintain AP mode for manual configuration if reconnection fails
- Track WiFi config and last reconnection attempt time in shared state
- Add wifi_try_reconnect_sta() and wifi_restore_ap_mode() helper functions
- Log reconnection attempts and results for debugging

src/main.cpp

@@ -112,6 +112,11 @@ void setup() {
   display_set_sender_statuses(g_receiver_shared.sender_statuses, NUM_SENDERS);
 
   bool has_cfg = wifi_load_config(g_cfg);
+  
+  // Store WiFi config in shared state for later reconnection attempts
+  g_receiver_shared.wifi_config = g_cfg;
+  g_receiver_shared.last_wifi_reconnect_attempt_ms = 0;
+  
   if (has_cfg && wifi_connect_sta(g_cfg)) {
     g_receiver_shared.ap_mode = false;
     time_receiver_init(g_cfg.ntp_server_1.c_str(), g_cfg.ntp_server_2.c_str());
@@ -124,6 +129,13 @@ void setup() {
     char ap_ssid[32];
     snprintf(ap_ssid, sizeof(ap_ssid), "%s%04X", AP_SSID_PREFIX, g_short_id);
     wifi_start_ap(ap_ssid, AP_PASSWORD);
+    
+    // Store AP credentials in shared state for potential reconnection fallback
+    strncpy(g_receiver_shared.ap_ssid, ap_ssid, sizeof(g_receiver_shared.ap_ssid) - 1);
+    g_receiver_shared.ap_ssid[sizeof(g_receiver_shared.ap_ssid) - 1] = '\0';
+    strncpy(g_receiver_shared.ap_password, AP_PASSWORD, sizeof(g_receiver_shared.ap_password) - 1);
+    g_receiver_shared.ap_password[sizeof(g_receiver_shared.ap_password) - 1] = '\0';
+    
     if (g_cfg.ntp_server_1.isEmpty()) {
       g_cfg.ntp_server_1 = "pool.ntp.org";
     }