[ld2450] Batch UART reads to reduce loop overhead

Read all available bytes in batches via read_array() instead of
byte-at-a-time read() calls. Each read() internally chains through
read_byte -> read_array(1) -> check_read_timeout_ -> available(),
resulting in 3 UART calls per byte. At 256000 baud with ~235 bytes
per loop iteration, this was ~706 UART operations per loop call.
Batching reduces this to ~12.

Measured 33% reduction in loop time (2348ms -> 1577ms per 60s).

esphome/components/ld2450/ld2450.cpp

@@ -276,8 +276,23 @@ void LD2450Component::dump_config() {
 }
 
 void LD2450Component::loop() {
-  while (this->available()) {
-    this->readline_(this->read());
+  int avail = this->available();
+  if (avail == 0) {
+    return;
+  }
+
+  // Read all available bytes in batches to reduce UART call overhead.
+  uint8_t buf[MAX_LINE_LENGTH];
+  while (avail > 0) {
+    size_t to_read = std::min(static_cast<size_t>(avail), sizeof(buf));
+    if (!this->read_array(buf, to_read)) {
+      break;
+    }
+    avail -= to_read;
+
+    for (size_t i = 0; i < to_read; i++) {
+      this->readline_(buf[i]);
+    }
   }
 }
 

esphome/components/pipsolar/pipsolar.cpp

@@ -13,12 +13,9 @@ void Pipsolar::setup() {
 }
 
 void Pipsolar::empty_uart_buffer_() {
-  uint8_t buf[64];
-  int avail;
-  while ((avail = this->available()) > 0) {
-    if (!this->read_array(buf, std::min(static_cast<size_t>(avail), sizeof(buf)))) {
-      break;
-    }
+  uint8_t byte;
+  while (this->available()) {
+    this->read_byte(&byte);
   }
 }
 
@@ -97,47 +94,32 @@ void Pipsolar::loop() {
   }
 
   if (this->state_ == STATE_COMMAND || this->state_ == STATE_POLL) {
-    int avail = this->available();
-    while (avail > 0) {
-      uint8_t buf[64];
-      size_t to_read = std::min(static_cast<size_t>(avail), sizeof(buf));
-      if (!this->read_array(buf, to_read)) {
+    while (this->available()) {
+      uint8_t byte;
+      this->read_byte(&byte);
+
+      // make sure data and null terminator fit in buffer
+      if (this->read_pos_ >= PIPSOLAR_READ_BUFFER_LENGTH - 1) {
+        this->read_pos_ = 0;
+        this->empty_uart_buffer_();
+        ESP_LOGW(TAG, "response data too long, discarding.");
         break;
       }
-      avail -= to_read;
-      bool done = false;
-      for (size_t i = 0; i < to_read; i++) {
-        uint8_t byte = buf[i];
+      this->read_buffer_[this->read_pos_] = byte;
+      this->read_pos_++;
 
-        // make sure data and null terminator fit in buffer
-        if (this->read_pos_ >= PIPSOLAR_READ_BUFFER_LENGTH - 1) {
-          this->read_pos_ = 0;
-          this->empty_uart_buffer_();
-          ESP_LOGW(TAG, "response data too long, discarding.");
-          done = true;
-          break;
+      // end of answer
+      if (byte == 0x0D) {
+        this->read_buffer_[this->read_pos_] = 0;
+        this->empty_uart_buffer_();
+        if (this->state_ == STATE_POLL) {
+          this->state_ = STATE_POLL_COMPLETE;
         }
-        this->read_buffer_[this->read_pos_] = byte;
-        this->read_pos_++;
-
-        // end of answer
-        if (byte == 0x0D) {
-          this->read_buffer_[this->read_pos_] = 0;
-          this->empty_uart_buffer_();
-          if (this->state_ == STATE_POLL) {
-            this->state_ = STATE_POLL_COMPLETE;
-          }
-          if (this->state_ == STATE_COMMAND) {
-            this->state_ = STATE_COMMAND_COMPLETE;
-          }
-          done = true;
-          break;
+        if (this->state_ == STATE_COMMAND) {
+          this->state_ = STATE_COMMAND_COMPLETE;
         }
       }
-      if (done) {
-        break;
-      }
-    }
+    }  // available
   }
   if (this->state_ == STATE_COMMAND) {
     if (millis() - this->command_start_millis_ > esphome::pipsolar::Pipsolar::COMMAND_TIMEOUT) {