fix: declare loop variable sa as const pointer in t5s3_epaper variant

[Copilot]

cppcheck static analysis was failing the check (t5s3_epaper_inkhud, esp32s3) CI job due to a [constVariablePointer] style violation.

Change

In src/platform/extra_variants/t5s3_epaper/variant.cpp, the range-for loop variable sa only reads sa->handleInput and never mutates the pointed-to object — const is correct here:

// before
for (NicheGraphics::InkHUD::SystemApplet *sa : inkhud->systemApplets) {

// after
for (const NicheGraphics::InkHUD::SystemApplet *sa : inkhud->systemApplets) {

🤝 Attestations

• I have tested that my proposed changes behave as described.
• I have tested that my proposed changes do not cause any obvious regressions on the following devices:
  • Heltec (Lora32) V3
  • LilyGo T-Deck
  • LilyGo T-Beam
  • RAK WisBlock 4631
  • Seeed Studio T-1000E tracker card
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