fix(per-client): Classify read encoder fn at dispatch SLOT 0, not +0x30

PCDIAG showed every per-client field classifying Unsupported despite a registration
hit. Classify read the encode fn as *(*(fieldInfo+0x38)+0x30); the real fn is dispatch
SLOT 0 = *(*(fieldInfo+0x38)) (verified: EncodeField decompile line 290 calls
**(fieldInfo+0x38); the +0x30 was a different call at line 285 = the recipients/proxy
table indexed by param_11). The emit path already used slot 0, so Classify was the only
gate wrongly rejecting. This was masked earlier by the empty encoder map.