fix: declare loop variable sa as const pointer in t5s3_epaper variant (#11111)

* Initial plan

* fix: declare sa as const pointer in t5s3_epaper variant.cpp

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Co-authored-by: copilot-swe-agent[bot] <198982749+Copilot@users.noreply.github.com>

Author: Copilot

src/platform/extra_variants/t5s3_epaper/variant.cpp

@@ -36,7 +36,7 @@ class TouchInkHUDBridge : public Observer<const InputEvent *>
 
         // Check whether a system applet (e.g. menu) is currently handling input
         bool systemHandlingInput = false;
-        for (NicheGraphics::InkHUD::SystemApplet *sa : inkhud->systemApplets) {
+        for (const NicheGraphics::InkHUD::SystemApplet *sa : inkhud->systemApplets) {
             if (sa->handleInput) {
                 systemHandlingInput = true;
                 break;