C cursor PyMemberDef widths don't match struct fields (OOB write → segfault)

Four MrdbCursor_Members entries declare a member type whose width doesn't match
the backing struct field, so the generated getter/setter touches the wrong
number of bytes:

arraysize T_LONG -> T_UINT (uint32_t row_array_size) – real bug
insert_id T_UINT -> T_ULONGLONG (uint64_t lastrow_id, RO) – truncation
_reprepare T_UINT -> T_UBYTE (uint8_t) – latent
_command T_BYTE -> T_INT (4-byte enum) – cosmetic

• arraysize: the 8-byte T_LONG store overruns the adjacent `paraminfo` pointer
  when cursor.arraysize is set; reads return garbage high bits.
• insert_id: the 4-byte read truncates auto-increment ids > 2^32.
• _reprepare: 4-byte store over a 1-byte field. Harmless (reprepare is
  followed by padding + weakreflist).
• _command: 1-byte accessor over a 4-byte enum; read-only with small values, so
  cosmetic.