[light] Force-inline ColorModeBitPolicy::to_bit

Although to_bit is constexpr and header-defined, the compiler leaves
it as an out-of-line function when called with a runtime ColorMode,
costing a call0/call8 for what is a short linear search over a 10-entry
compile-time table. Marking it ESPHOME_ALWAYS_INLINE lets the compiler
fold the lookup into each caller (validate_, color_mode_to_human,
get_suitable_color_modes_mask_, light_json_schema). The to_bit symbol
disappears from the link output entirely.

Flash delta is small (+16 B ESP8266, +44 B ESP32-IDF in isolated light
build); the intent is the runtime win — CodSpeed will quantify it.

esphome/components/light/color_mode.h

@@ -2,6 +2,7 @@
 
 #include <cstdint>
 #include "esphome/core/finite_set_mask.h"
+#include "esphome/core/helpers.h"  // ESPHOME_ALWAYS_INLINE
 
 namespace esphome::light {
 
@@ -128,7 +129,7 @@ struct ColorModeBitPolicy {
   using mask_t = uint16_t;  // 10 bits requires uint16_t
   static constexpr int MAX_BITS = sizeof(COLOR_MODE_LOOKUP) / sizeof(COLOR_MODE_LOOKUP[0]);
 
-  static constexpr unsigned to_bit(ColorMode mode) {
+  static constexpr unsigned ESPHOME_ALWAYS_INLINE to_bit(ColorMode mode) {
     // Linear search through lookup table
     // Compiler optimizes this to efficient code since array is constexpr
     for (int i = 0; i < MAX_BITS; ++i) {