revert: restore pre-4b59b89 web server (drop chunked API + low-memory auto-reboot)

The chunked API handlers and the maxblock<6000 auto-restart from 4b59b89
broke the web UI on-device; restore the working String-based handlers and
plain loop while keeping the scrollable forecast log.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

WeatherPredictor/WeatherPredictor.ino

@@ -88,15 +88,6 @@ void loop() {
     tSample = now;
     sampleNow();
     displayRender(g_state);
-    Serial.printf("heap=%u maxblock=%u\n", ESP.getFreeHeap(), ESP.getMaxFreeBlockSize());
-    // Safety net: if the largest contiguous block gets too small, the TCP stack
-    // can no longer send responses. Persist and reboot to defragment.
-    if (ESP.getMaxFreeBlockSize() < 6000) {
-      Serial.println(F("Low memory -> saving history and restarting"));
-      historySave();
-      delay(50);
-      ESP.restart();
-    }
   }
 
   if (now - tHistory >= HISTORY_INTERVAL_MS) {