Rename power.h to Power.h for casing consistency with Power.cpp (#10919)

Every other .cpp/.h pair in src/ (350 of 351) uses identical
capitalization between the two files. Power.cpp/power.h was the sole
outlier; this aligns it with the rest of the codebase. No functional
change — all includes already resolved this file the same way on
case-sensitive filesystems.

Assisted-by: Claude Sonnet 5 <noreply@anthropic.com>

Signed-off-by: Andrew Yong <me@ndoo.sg>
Co-authored-by: Ben Meadors <benmmeadors@gmail.com>

src/input/ButtonThread.cpp

@@ -6,13 +6,13 @@
 #include "GPS.h"
 #endif
 #include "MeshService.h"
+#include "Power.h"
 #include "RadioLibInterface.h"
 #include "buzz.h"
 #include "input/InputBroker.h"
 #include "main.h"
 #include "modules/CannedMessageModule.h"
 #include "modules/ExternalNotificationModule.h"
-#include "power.h"
 #include "sleep.h"
 #ifdef ARCH_PORTDUINO
 #include "platform/portduino/PortduinoGlue.h"