feat(Power): support EXT_PWR_DETECT_MODE & EXT_PWR_DETECT_VAL, simplify EXT_PWR_DETECT

[ndoo]

Motivation: Simplify future variants by allowing to use internal pull-up/pull-down resistors, thus eliminating a physical resistor on the PCB.

• Also adds feature parity to EXT_CHG_DETECT which supports custom modes and high/low state already.
• Support the use of custom GPIO mode for EXT_PWR_DETECT GPIO pin, which allows the use of INPUT_PULLDOWN and INPUT_PULLUP on MCUs which have internal pull-up or pull-down resistors supported in Arduino.
• Migrate heltec_capsule_sensor_v3 and heltec_sensor_hub from inline ifdef hacks to EXT_PWR_DETECT_MODE.
• Support the use of EXT_PWR_DETECT_VAL which allows both internal or external pull-down resistors to be used for EXT_PWR_DETECT. Automatically set the appropriate EXT_PWR_DETECT_VAL if internal pull resistors are used.
• Simplified EXT_PWR_DETECT by comparing with EXT_PWR_DETECT_VAL directly and remove heltec_capsule_sensor_v3 and heltec_sensor_hub #ifdef hacks now that EXT_PWR_DETECT_VAL is used.

Clean up the comments for isVbusIn() while I am here.

Build tested on:

• heltec_capsule_sensor_v3
• heltec_sensor_hub
• heltec-v3 (as a regression test)
• russell (not in this PR, working on a bunch of enhancements seperately)

Functionality tested on:

• russell (not in this PR, working on a bunch of enhancements seperately)

🤝 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
  • Other (please specify below)
  • Testers needed, especially heltec_capsule_sensor_v3 & heltec_sensor_hub, I don’t have these devices but they are using hacks that this PR removes in favor of proper implementation

[ndoo]

That being said, EXT_CHRG_DETECT is out of scope of this PR but I think needs a cleanup too, as it currently stores its defines in a runtime uint8_t variable unnecessarily - because it never changes in runtime, it should just be handled by preprocessor directives.

[Copilot]

Pull request overview

Adds configurable external power detection behavior to the Power subsystem so board variants can use internal GPIO pull-ups/pull-downs (and configurable active level) instead of hardcoded per-board hacks.

Changes:

• Introduces EXT_PWR_DETECT_MODE (and inferred/defaulted EXT_PWR_DETECT_VAL) handling in src/Power.cpp.
• Simplifies isVbusIn() to compare digitalRead(EXT_PWR_DETECT) directly against EXT_PWR_DETECT_VAL.
• Updates Heltec ESP32-S3 variants to use EXT_PWR_DETECT_MODE INPUT_PULLUP instead of special-case #ifdef logic.

Reviewed changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated 1 comment.

File	Description
src/Power.cpp	Adds EXT_PWR_DETECT_MODE/EXT_PWR_DETECT_VAL handling, removes Heltec-specific conditionals, simplifies external power detection and pin setup.
variants/esp32s3/heltec_capsule_sensor_v3/variant.h	Sets EXT_PWR_DETECT_MODE to INPUT_PULLUP for this variant.
variants/esp32s3/heltec_sensor_hub/variant.h	Sets EXT_PWR_DETECT_MODE to INPUT_PULLUP for this variant.

[ndoo]

Renamed EXT_PWR_DETECT_VAL → EXT_PWR_DETECT_VALUE for consistency with ext-chrg-detect.

Rebased on develop HEAD (as of now) to keep fresh.