Improve meter ingestion resilience under UART gaps

src/meter_driver.cpp

@@ -4,9 +4,9 @@
 #include <stdlib.h>
 #include <string.h>
 
-// LoRa TX/RX windows can block the main loop for several seconds at SF12.
-// Keep partial frame state long enough so valid telegrams are not dropped.
-static constexpr uint32_t METER_FRAME_TIMEOUT_MS = 20000;
+// Dedicated reader task pumps UART continuously; keep timeout short so parser can
+// recover quickly from broken frames.
+static constexpr uint32_t METER_FRAME_TIMEOUT_MS = 3000;
 static constexpr size_t METER_FRAME_MAX = 512;
 
 enum class MeterRxState : uint8_t {
@@ -142,6 +142,13 @@ bool meter_poll_frame(const char *&frame, size_t &len) {
       continue;
     }
 
+    // Fast resync if a new telegram starts before current frame completed.
+    if (c == '/') {
+      g_frame_len = 0;
+      g_frame_buf[g_frame_len++] = c;
+      continue;
+    }
+
     if (g_frame_len + 1 >= sizeof(g_frame_buf)) {
       g_rx_overflow++;
       g_rx_state = MeterRxState::WaitStart;