Replace optional<ProtoVarInt> + consumed pointer with ProtoVarIntResult
struct that returns value + consumed count directly. This eliminates
memory stores through a pointer on the fast path (single-byte varints
< 128), keeping everything in registers.
The parse() method is now ESPHOME_ALWAYS_INLINE with the multi-byte
slow path outlined to parse_slow_(). The common case for protobuf
field tags, small enums, booleans, and typical message sizes/types
is a simple high-bit check + register return with no function call.
Measured on ESP32 (Xtensa): try_read_frame_ grows only +12 bytes
(320 → 332) for two inlined parse sites, while eliminating two
function calls per message on the hot path.
J. Nick Koston
e285fd6815