docs(quickadapter): define backtest evaluation protocol (#154)

docs(quickadapter): define backtest evaluation protocol (#154)

* docs(quickadapter): define backtest evaluation protocol

* docs(quickadapter): unify outer prediction window terminology

Harmonize the lone bare "outer window" in the backtest evaluation protocol nested-HPO step with the "outer prediction window" term used elsewhere in the section, removing an ambiguous synonym for the rolling-origin evaluation window (distinct from the "outer holdout").

* docs(quickadapter): harmonize backtest-protocol terminology and qualify drawdown bootstrap

- clarify the row-wise known_at_lookahead maximum spans label and weight availability values
- use code font consistently for continual_learning
- align the label-candle shuffling seed role with the configuration tunables table
- name log returns explicitly before the positivity requirement
- unify "latest retained information time" across the purge step
- note the maximum-drawdown bootstrap bound is approximate for a non-smooth path-dependent functional

* docs(quickadapter): gate step 8 effect-size bootstrap on stationarity credibility

Make the stationary-bootstrap applicability in step 8 symmetric with the
Reality Check/SPA gate in step 9: declare the result inconclusive when the
paired series' stationarity and local-dependence assumptions are not credible
under a fixed or moving-window scheme. Addresses the outstanding PR #154 review
comment on the step 8 vs step 9 stationarity asymmetry.

* docs(quickadapter): harmonize primary-metric naming and fix spelling

- name the step 9 promotion bound the "net-log-return effect", consistent with
  the step 7-8 net-log-return inference and the positive-is-favorable effect
  terminology (removes the one-off "net-growth" synonym for the same estimand)
- correct "relabelled" to "relabeled" for US-English consistency