Sync protobuf changes for FixedVector support in BLE characteristics and descriptors (#1393)

Author: bdraco

aioesphomeapi/api.proto

@@ -1519,7 +1519,7 @@ message BluetoothGATTCharacteristic {
   repeated uint64 uuid = 1 [(fixed_array_size) = 2, (fixed_array_skip_zero) = true];
   uint32 handle = 2;
   uint32 properties = 3;
-  repeated BluetoothGATTDescriptor descriptors = 4;
+  repeated BluetoothGATTDescriptor descriptors = 4 [(fixed_vector) = true];
 
   // New field for efficient UUID (v1.12+)
   // Only one of uuid or short_uuid will be set.
@@ -1531,7 +1531,7 @@ message BluetoothGATTCharacteristic {
 message BluetoothGATTService {
   repeated uint64 uuid = 1 [(fixed_array_size) = 2, (fixed_array_skip_zero) = true];
   uint32 handle = 2;
-  repeated BluetoothGATTCharacteristic characteristics = 3;
+  repeated BluetoothGATTCharacteristic characteristics = 3 [(fixed_vector) = true];
 
   // New field for efficient UUID (v1.12+)
   // Only one of uuid or short_uuid will be set.

aioesphomeapi/api_options.proto

@@ -64,4 +64,10 @@ extend google.protobuf.FieldOptions {
     // This is typically done through methods returning const T& or special accessor
     // methods like get_options() or supported_modes_for_api_().
     optional string container_pointer = 50001;
+
+    // fixed_vector: Use FixedVector instead of std::vector for repeated fields
+    // When set, the repeated field will use FixedVector<T> which requires calling
+    // init(size) before adding elements. This eliminates std::vector template overhead
+    // and is ideal when the exact size is known before populating the array.
+    optional bool fixed_vector = 50013 [default=false];
 }