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/modules/Telemetry/EnvironmentTelemetry.cpp

@@ -7,6 +7,7 @@
 #include "EnvironmentTelemetry.h"
 #include "MeshService.h"
 #include "NodeDB.h"
+#include "Power.h"
 #include "PowerFSM.h"
 #include "RTC.h"
 #include "Router.h"
@@ -17,7 +18,6 @@
 #include "graphics/images.h"
 #include "main.h"
 #include "modules/ExternalNotificationModule.h"
-#include "power.h"
 #include "sleep.h"
 #include "target_specific.h"
 #include <OLEDDisplay.h>