feat(v2): stabilize VBUS readout filtering

[kawinie]

Summary

The supply readout jittered under V_SENSE divider noise, and the load readout twitched downward after the output toggled on. This PR adds three layered fixes so the displayed voltage stays steady at rest and snaps cleanly on PDO transitions.

• ADC samples are oversampled 64× per read for sqrt(N) noise reduction on uncorrelated jitter, around 300 µs loop time and negligible vs the 40 ms sensor period.
• Filter::ema gains an optional snap threshold so deltas above the threshold (PDO step changes) bypass smoothing and replace the prior value. EMA methods now live on LoadReading/SupplyReading with their own tuned constants.
• On OFF→ON toggle, the load EMA is seeded with the current supply value, and the first two INA226 samples are discarded so a stale conversion (latched while the FET was off, ~200 mV) does not contaminate the seed.

Also inlines the pin map into pocketpd.h (drops the PocketPDPinOut dependency) and renames evt → event in two stage handlers.

Linked issues

Hardware tested

• HW1_3

How tested: Flashed HW1_3. Confirmed supply readout no longer jitters at rest. Toggled output OFF→ON across 5 V and 20 V profiles. Display now seeds to the supply value and converges to the load reading without the previous downward droop. PDO switching still snaps to the new voltage immediately.

Breaking change / migration

Details:

Notes

The .clang-format change adds PenaltyReturnTypeOnItsOwnLine: 1000 to keep return types on the same line as the function name. Carry-over from local config, included for consistency with how the touched files are now formatted.