AtlasSpigot 26.2 - v11 (systematic bug audit, all clean)

Change from v10 - no jar changes, a systematic verification pass:

Cross-referenced every currently-enabled setting against Leaf's full list of @Experimental/@Deprecated-annotated config modules (grepped from actual source, not guessed) - async-chunk-send, async-playerdata-save, DAB, optimized-powered-rails, region-format, redstone-implementation, dont-save-primed-tnt/falling-block, reduce-packets, only-tick-items-in-hand. None of them are flagged. Also re-searched Leaf's issue tracker for open reports on B_LINEAR, ALTERNATE_CURRENT, powered rails, DAB, and dont-save specifically - zero hits.

Confirmed as a side effect: every setting left off back in the very first review round as merely 'ambiguous' is actually also on the Experimental/Deprecated list - that early caution turns out to have been correct for a concrete, checkable reason, not just instinct.

Documented the actual screening checklist in the README (patch review, upstream caution-flag check, issue search, full-log boot, a real functional check - applied periodically to existing settings too, not just new ones). That process is what caught the entity-activation regression last release.

Same jar as v10 - see README for the full breakdown and the new methodology section.