refactor(super-chess-bot): remove variant support and Fairy-Stockfish

Pure standard chess plus Chess960 on a single orthodox Stockfish
worker. Non-standard variants fail closed on both site adapters.
Drops dead variant plumbing (pendingVariantUpdates, engineVariant,
supportsDrops), prunes the fairy lockfile entry, rebuilds both
bundles, removes two stale pre-refactor handoff docs, and bumps
vitest 5.0.3 to 5.0.4. bun run check passes: biome, tsc, knip,
316 tests across 28 files, both production builds.

Author: quantavil

super-chess-bot/AGENTS.md

@@ -4,7 +4,7 @@
 
 - Use Bun for package installation, scripts, and tests. Run `bun install --frozen-lockfile` and `bun run check` from this directory.
 - Keep both production outputs: `dist/bundle.user.js` for Chess.com and Lichess, and `dist/chesscom.user.js` for Chess.com alone.
-- Keep package metadata, userscript headers, and `LICENSE` at GPL-3.0-or-later. Preserve version-pinned Stockfish/Fairy-Stockfish resource URLs and SHA-256 hashes when changing engine resources.
+- Keep package metadata, userscript headers, and `LICENSE` at GPL-3.0-or-later. Preserve version-pinned Stockfish resource URLs and SHA-256 hashes when changing engine resources.
 - CI uses Bun 1.4.2 and runs the frozen install plus `bun run check` for changes under this project or its workflow.
 
 ## Architecture boundaries
@@ -15,9 +15,9 @@ Use one owned engine worker at a time. Validate current session and position bef
 
 ## Supported runtime
 
-- The current supported game scope is standard player games on Chess.com and Lichess. Automation starts disabled.
+- The current supported game scope is standard player games on Chess.com and Lichess (including Chess960). Automation starts disabled.
 - PyChess has been removed from runtime, tests, host matches and userscript metadata. Old handoffs and browser records mentioning PyChess are historical and are not support claims.
-- Keep shared variant identity normalization for future use. Full variant move transport on Chess.com and Lichess is deferred; do not document variants as fixed or currently supported.
+- Non-standard and fairy variants are not supported. Fairy-Stockfish is completely removed.
 - Chess.com positions are controller-local observations. Lichess positions come from validated site-owned round steps. See [docs/support-matrix.md](docs/support-matrix.md).
 
 ## Behavior constraints

super-chess-bot/README.md

@@ -8,7 +8,7 @@ A GPL-3.0-or-later browser userscript for local chess analysis and move automati
 
 ## What it does
 
-- Runs Stockfish locally in a worker. The multi-site build also includes Fairy-Stockfish and a shared variant registry; complete variant move transport on either site remains experimental and is not part of the supported game matrix.
+- Runs Stockfish locally in a worker for standard chess and Chess960 games.
 - Reads and submits standard moves through each site's controller integration. Automation starts disabled.
 - Shows up to three engine lines, optional opening-book choices, and a local scoresheet with PGN export.
 - Offers an on-demand post-game report. Its search defaults to depth 18, can be set from depth 10 to 26, and runs only after the adapter reports a finished game.