[MEM] Reduce ESP32 BLE firmware RAM usage (#2294)

- Fix addLog buffer overflow; reduce LOG_BUFFER_SIZE 6096→3072, ROW_LENGTH 1024→512
- Lazy-allocate web console log buffer (saves ~3.5KB when console not active)
- Stream WebUI responses in chunks to eliminate String heap allocations
- NimBLE buffer tuning: ACL bufs 20→12, HCI hi bufs 30→15, MSYS1 blocks 12→8, MTU 256→185
- BLE adv report flow control 100→50, LWIP sockets 16→10
- BLE scan duplicate cache 200→100 (align with sdkconfig)
- procBLETask stack 9500→8000 (788B headroom over measured peak)
- Cap BLE device vector at 80 with LRU eviction of non-listed devices
- Disable unused LWIP components: PPP, IPv6 autoconfig/DHCPv6
- Disable unused Arduino libs: SD, SD_MMC, FFat, LittleFS, NetBIOS

Measured over 30 min A/B test vs development:
  freemem: 58,805 → 68,755 avg (+10KB)
  minmem:  5,988 → 15,780 (+9.8KB)
  msgprc/scnct: identical (656 msgs, 26 scans)
  msgblck: 0 on both branches
  No crashes or errors

Co-authored-by: Florian <1technophile@users.noreply.github.com>
Co-authored-by: Claude Opus 4.6 <noreply@anthropic.com>

main/gatewayBT.cpp

@@ -372,6 +372,23 @@ void createOrUpdateDevice(const char* mac, uint8_t flags, int model, int mac_typ
   }
   BLEdevice* device = getDeviceByMac(mac);
   if (device == &NO_BT_DEVICE_FOUND) {
+    // Evict oldest non-listed device when at capacity
+    if ((int)devices.size() >= MaxBLEDevices) {
+      int oldestIdx = -1;
+      unsigned long oldestTime = ULONG_MAX;
+      for (int i = 0; i < (int)devices.size(); i++) {
+        if (!devices[i]->isWhtL && !devices[i]->isBlkL && !devices[i]->connect &&
+            devices[i]->lastUpdate < oldestTime) {
+          oldestTime = devices[i]->lastUpdate;
+          oldestIdx = i;
+        }
+      }
+      if (oldestIdx >= 0) {
+        THEENGS_LOG_TRACE(F("%.4s evict %s" CR), "BLE", devices[oldestIdx]->macAdr);
+        delete devices[oldestIdx];
+        devices.erase(devices.begin() + oldestIdx);
+      }
+    }
     THEENGS_LOG_TRACE(F("add %s" CR), mac);
     //new device
     device = new BLEdevice();
@@ -889,7 +906,7 @@ void setupBTTasksAndBLE() {
 #  if defined(USE_ESP_IDF) || defined(USE_BLUFI)
       14500,
 #  else
-      9500, /* Stack size in bytes */
+      8000, /* Stack size in bytes */
 #  endif
       NULL, /* Task input parameter */
       2, /* Priority of the task (set higher than core task) */