feat: sketch scaffold with I2C bus bring-up and scanner

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

WeatherPredictor/WeatherPredictor.ino

@@ -0,0 +1,27 @@
+#include <Arduino.h>
+#include <Wire.h>
+#include "config.h"
+
+static void i2cScan() {
+  Serial.println(F("I2C scan:"));
+  byte found = 0;
+  for (byte addr = 1; addr < 127; addr++) {
+    Wire.beginTransmission(addr);
+    if (Wire.endTransmission() == 0) {
+      Serial.printf("  device at 0x%02X\n", addr);
+      found++;
+    }
+  }
+  Serial.printf("  %d device(s) found\n", found);
+}
+
+void setup() {
+  Serial.begin(115200);
+  delay(200);
+  Serial.println(F("\n=== Weather Predictor booting ==="));
+  Wire.begin(I2C_SDA, I2C_SCL);   // MUST come before any I2C driver begin()
+  i2cScan();
+}
+
+void loop() {
+}

WeatherPredictor/config.h

@@ -0,0 +1,34 @@
+#pragma once
+#include <Arduino.h>
+
+// ---- TFT (hardware SPI: SCK=D5, MOSI=D7) ----
+#define TFT_CS   D8
+#define TFT_DC   D3
+#define TFT_RST  D4
+#define TFT_BLK  D2
+
+// ---- I2C (BMP180 + DS3231 share this bus) ----
+#define I2C_SDA  D6
+#define I2C_SCL  D1
+#define BMP180_ADDR 0x77
+#define DS3231_ADDR 0x68
+
+// ---- Scheduler intervals (ms) ----
+// NOTE: for quick bench testing you may temporarily shrink these.
+static const unsigned long SAMPLE_INTERVAL_MS  = 60UL * 1000UL;         // read sensor / redraw
+static const unsigned long HISTORY_INTERVAL_MS = 5UL * 60UL * 1000UL;   // store a history sample
+static const unsigned long FLUSH_INTERVAL_MS   = 15UL * 60UL * 1000UL;  // flush history to flash
+
+// ---- History buffer ----
+static const int   HISTORY_SIZE        = 288;   // 24 h @ 5 min
+static const float TREND_THRESHOLD_HPA = 1.6f;  // >|1.6| hPa / 3 h = rising/falling
+
+// ---- Defaults (editable via web) ----
+static const float DEFAULT_ALTITUDE_M    = 150.0f;
+static const int   DEFAULT_TZ_OFFSET_MIN = 7 * 60; // UTC+7
+static const float DEFAULT_LAT           = 54.9870f;
+static const float DEFAULT_LON           = 82.8730f;
+
+// ---- Network ----
+#define NTP_SERVER "pool.ntp.org"
+#define AP_NAME    "WeatherPredictor-Setup"