feat(fmt/pdb): don't guess in reader

[jnooree]

Checklist

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[codecov]

Codecov Report

Attention: Patch coverage is 88.23529% with 4 lines in your changes missing coverage. Please review.

Project coverage is 91.32%. Comparing base (d1586db) to head (71c2cfc).
Report is 10 commits behind head on main.

Files with missing lines	Patch %	Lines
python/src/nuri/fmt/fmt_module.cpp	70.00%	3 Missing ⚠️
src/fmt/pdb.cpp	92.30%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #437      +/-   ##
==========================================
+ Coverage   91.17%   91.32%   +0.14%     
==========================================
  Files          52       52              
  Lines       12779    12629     -150     
==========================================
- Hits        11651    11533     -118     
+ Misses       1128     1096      -32     

Files with missing lines	Coverage Δ
include/nuri/fmt/base.h	100.00% <ø> (ø)
include/nuri/fmt/mol2.h	100.00% <100.00%> (ø)
include/nuri/fmt/pdb.h	100.00% <100.00%> (ø)
include/nuri/fmt/sdf.h	100.00% <100.00%> (ø)
include/nuri/fmt/smiles.h	100.00% <100.00%> (ø)
src/algo/guess/3d.cpp	84.52% <100.00%> (+0.08%)	⬆️
src/fmt/pdb.cpp	91.89% <92.30%> (+3.38%)	⬆️
python/src/nuri/fmt/fmt_module.cpp	91.00% <70.00%> (-2.55%)	⬇️

... and 1 file with indirect coverage changes