feat: HTTP server with REST API for current/history/settings

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

WeatherPredictor/WeatherPredictor.ino

@@ -8,6 +8,7 @@
 #include "history.h"
 #include "app_settings.h"
 #include "net.h"
+#include "web_server.h"
 #include "state.h"
 
 AppState g_state;
@@ -67,10 +68,15 @@ void setup() {
   sampleNow();
   historyAdd(rtcEpoch(), g_state.mslHpa, g_state.tempC);
   displayRender(g_state);
+
+  webBegin();
+  if (netConnected()) Serial.printf("Web UI: http://%s/\n", netIP().c_str());
+
   tSample = tHistory = tFlush = millis();
 }
 
 void loop() {
+  webLoop();
   unsigned long now = millis();
 
   if (now - tSample >= SAMPLE_INTERVAL_MS) {