Cap an addressable strip's estimated current draw to a PSU budget so bright/
white scenes can't brown out an under-spec'd supply (voltage sag -> red/orange
shift, flicker, controller resets) — a classic 'it's broken' first impression.
- New core/processing/power_limit.py: pure current estimate (full white over N
LEDs draws N * mA_per_led) + a (0,1] scale to land a frame on budget.
- Applied in WledTargetProcessor._send_to_device (single choke point, every send
path; scales into a reusable scratch buffer, never mutates shared frames).
- Two per-target fields on LED targets: max_milliamps (0 = unlimited) and
milliamps_per_led (default 55), threaded through model/store/manager/processor/
schema/route with hot-update via update_target_settings. Additive with safe
defaults (no data migration needed; legacy targets read as unlimited).
- Frontend: editor fields + i18n (en/ru/zh) + LedOutputTarget type.
- Tests: 10 unit tests for the estimator/scale; full suite green (1911 passed).
