Fix sp_dump AccessViolation crash + add read-only EncodeField detour probe

sp_dump crashed the server: speculative qword-scanning + multi-field-record derefs hit an
unmapped page → AccessViolationException (uncatchable in .NET → process abort). Layout's
already confirmed, so reduced sp_dump to the proven-safe reads only (classInfo name/count/
array + field[0] name via the confirmed +0x08 offset); no speculative reads.

Added EncodeFieldDetour: read-only IDetourHook passthrough on EncodeField (resolved by the
verified byte-sig). Captures the 6 SysV arg registers + return, logs the first 24 calls,
calls the original unchanged. sp_detour_on/off commands. Verified install + 2h uptime live;
needs a connected client to actually fire (EncodeField only runs during per-client snapshot).

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>