fix: skip NTP sync and mDNS in deep sleep wake path to reduce battery drain

The syncNTP() call blocks up to 5 seconds waiting for NTP response on
every deep sleep wake cycle (every 10 minutes). Combined with mDNS
startup, this added significant active WiFi time per cycle.

Fix: Add 'minimal' flag to WiFiManager::begin()/startStation(). In
the deep sleep wake path, skip NTP sync and mDNS entirely. The system
clock is already seeded from the hardware RTC at boot, which is
accurate enough for 30-day date window calculations.

Normal interactive boot still does full NTP sync + mDNS as before.

Co-authored-by: Cursor <cursoragent@cursor.com>

src/main.cpp

@@ -429,8 +429,8 @@ void timerWakeCycle() {
 
     Settings s = settingsManager.get();
 
-    // Connect WiFi (blocking)
-    wifiManager.begin(settingsManager);
+    // Connect WiFi (minimal — skip NTP/mDNS to save battery)
+    wifiManager.begin(settingsManager, true);
     if (!wifiManager.isConnected()) {
         Serial.println("[timer_wake] WiFi failed — going back to sleep");
         powerManager.enterDeepSleep(s.interval_min);

src/wifi_manager.cpp

@@ -6,7 +6,7 @@
 #include <sys/time.h>
 #include "config.h"
 
-void WiFiManager::begin(SettingsManager& settings) {
+void WiFiManager::begin(SettingsManager& settings, bool minimal) {
     _settings = &settings;
 
     if (!_settings->isProvisioned()) {
@@ -15,7 +15,7 @@ void WiFiManager::begin(SettingsManager& settings) {
         return;
     }
 
-    startStation();
+    startStation(minimal);
 }
 
 bool WiFiManager::isConnected() {
@@ -47,18 +47,26 @@ void WiFiManager::startAP() {
                   WiFi.softAPIP().toString().c_str());
 }
 
-void WiFiManager::startStation() {
+void WiFiManager::startStation(bool minimal) {
     Settings s = _settings->get();
     WiFi.disconnect(true);
     WiFi.mode(WIFI_STA);
     _apMode = false;
 
-    Serial.printf("[wifi] Connecting to: %s\n", s.wifi_ssid.c_str());
+    Serial.printf("[wifi] Connecting to: %s%s\n", s.wifi_ssid.c_str(),
+                  minimal ? " (minimal)" : "");
 
     for (_retryCount = 0; _retryCount < WIFI_MAX_RETRIES; _retryCount++) {
         if (attemptConnection(s.wifi_ssid, s.wifi_pass)) {
             Serial.printf("[wifi] Connected! IP: %s, RSSI: %d\n",
                           WiFi.localIP().toString().c_str(), WiFi.RSSI());
+
+            if (minimal) {
+                // Deep sleep wake path: skip NTP/mDNS to minimize active time.
+                // System clock was already seeded from hardware RTC at boot.
+                return;
+            }
+
             WiFi.setSleep(WIFI_PS_MIN_MODEM);
             syncNTP();
             setupMDNS("papercolor");

src/wifi_manager.h

@@ -5,13 +5,13 @@
 
 class WiFiManager {
 public:
-    void begin(SettingsManager& settings);
+    void begin(SettingsManager& settings, bool minimal = false);
     bool isConnected();
     bool isAPMode();
     String getIP();
     int getRSSI();
     void startAP();
-    void startStation();
+    void startStation(bool minimal = false);
     void setupMDNS(const char* hostname);
     void syncNTP();