fix: correct operator precedence in ForAllFields reverse iteration

[Tulgaaaaaaaa]

Problem

ForAllFields() in src/reflection.cpp:392 has an operator precedence bug when iterating fields in reverse order. The expression size() - i + 1 evaluates as (size() - i) + 1 due to C++ left-to-right associativity, instead of the intended size() - (i + 1).

For a 3-field object at i=0, this produces index 3 + 1 = 4, which is 2 past the last valid index (0, 1, 2). This causes an out-of-bounds read on every call to ForAllFields with reverse=true.

The correct expression size() - (i + 1) is already used in the parallel implementation at bfbs_gen.h:192.

Fix

Changed field_to_id_map.size() - i + 1 to field_to_id_map.size() - (i + 1) to match bfbs_gen.h.

i	Before (buggy)	After (fixed)
0	size()+1 (OOB)	size()-1 (last)
1	size() (OOB)	size()-2
2	size()-1	size()-3 (first)

Tests added

• ForAllFieldsReverseTest in tests/reflection_test.cpp
• Tests both Stat (3 fields) and Monster (many fields, non-sequential IDs) tables
• Verifies correct forward and reverse ID ordering

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