Try-fix: L76K spamming bad times can crash nodes

[thebentern]

I have seen this bug in the wild for a while now, but it's sporadic. This is an attempt to fix it by clearing the GPS buffer when we see it occur.

Fixed a couple of warnings in there as well

[Copilot]

Pull Request Overview

This PR aims to prevent node crashes caused by persistent bad GPS times by clearing the GPS buffer on invalid timestamps, and also cleans up compiler warnings around loop variable types and RTC-setting return values.

• Switched loop counters from signed to unsigned types to resolve warnings.
• Added an explicit notificationTypeEnum::none case in drawBannerCallback.
• Converted perhapsSetRTC from a boolean to an RTCSetResult enum and clear the GPS buffer on invalid time.
• Introduced the RTCSetResult enum to better represent RTC-set outcomes.

Reviewed Changes

Copilot reviewed 4 out of 4 changed files in this pull request and generated 1 comment.

File	Description
src/graphics/draw/NotificationRenderer.cpp	Updated loop indices to unsigned and added none case in switch
src/gps/RTC.h	Added RTCSetResult enum and updated perhapsSetRTC signatures
src/gps/RTC.cpp	Changed perhapsSetRTC implementations to return RTCSetResult
src/gps/GPS.cpp	Clear GPS buffer when perhapsSetRTC returns InvalidTime

Comments suppressed due to low confidence (3)

src/gps/RTC.h:28

• The comment for RTCSetResultNotSet is misleading—it indicates success. It should describe that the RTC was not updated (e.g., "RTC not set because a higher-quality time was already in place").

    RTCSetResultNotSet = 0,      ///< RTC was set successfully

src/gps/RTC.h:28

• [nitpick] RTCSetResultNotSet is ambiguous given its current semantic; consider renaming it to something like RTCSetResultSkipped or RTCSetResultAlreadySet to better convey that the RTC wasn’t updated.

    RTCSetResultNotSet = 0,      ///< RTC was set successfully

src/gps/GPS.cpp:1539

• Add or extend unit tests to verify that clearBuffer() is indeed called when perhapsSetRTC yields InvalidTime, ensuring this branch is exercised.

            if (perhapsSetRTC(RTCQualityGPS, t) == RTCSetResultInvalidTime) {