Cobbledex for REI / EMI / JEI

Removed

• Dead getClientDatapacksDir() function (never called after runtime API switch)
• Dead localDatapackScan config field (always true, conditional never triggered)
• Dead CONFIG_VERSION constant (defined but never checked)
• Dead SpeciesNameNormalizer.matches() function (zero call sites)
• Dead extraDatapacksDir parameter from ObtainmentDataLoader (always null)
• Old config filename migration code (all users migrated long ago)
• Stale bin/ directories containing old server sync compiled artifacts

Fixed

• Misleading "server sync" text in retry log message