Third detector rule: flag hours where target − reference falls below
-deviation_mw for at least deviation_slots consecutive native-cadence
slots, with the published day-ahead forecast as the reference column.
Dropout-only by design — the 2026-06 incident class is exclusively
negative (observed to −16.6 GW under the forecast) while staying below
the dynamics thresholds (2026-06-07 frontier: 5.6 GW steps under the
6 GW limit at Actual − Forecast = −11.6 GW), so level-vs-reference is
the discriminator the range/step rules cannot see.

Semantics:
- inert-by-default: new knobs target_qc_deviation_mw/_ref/_slots default
  to None/None/2; pipeline stays byte-identical when unset
- frontier-safe: NaN in either column compares False, so the
  publication-lag tail never flags and a gap breaks a consecutive run
- missing reference column skips the rule silently (mirrors absent
  target handling); reference is never NaN-ed by heal/truncate when
  targets are scoped to the actuals

Plumbed through ConfigEntsoe/ConfigMulti, validate_config, and the
prepare_data call site (detector activation now includes deviation-only
configurations).

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

…arget-qc-deviation-rule

feat(preprocessing): add deviation rule to target-corruption detector

## [18.1.0-rc.1](v18.0.1...v18.1.0-rc.1) (2026-06-07)

### Features

* **preprocessing:** add deviation rule to target-corruption detector ([95d45d2](95d45d2))

### Documentation

* add live {python} Examples to all public symbols missing them ([5fac4ca](5fac4ca))