fix(code_quality): do not deduct for public members in struct bodies

The public_member_variable rule previously applied uniformly to both
class and struct bodies, treating any public data member as a
code-quality finding regardless of the enclosing type. In C++ a struct
has public access by default and public data members are the idiomatic
shape for POD aggregates, value types, configuration data, and mixin
tags; penalising them charges the author for writing legitimate,
intended C++.

Gate the finding in analyze_class_blocks on kind == 'class'. struct
bodies — including struct members that appear inside an explicit
'public:' access block — no longer produce public_member_variable
findings. class bodies keep the existing behaviour: public data members
in a class continue to be deducted because the author of a class is
expected to encapsulate state.

Update the inline comment to explain the rationale so future readers
understand why struct and class are treated differently.

Reproducer:
  struct A { int counter; double value; };
  used to report 2 findings (counter, value); now 0.
  class B { public: int counter; double value; };
  still reports 2 findings.

Author: abacus_fixer

tools/03_code_analysis/code_quality_score.py

@@ -1390,7 +1390,13 @@ def analyze_class_blocks(
             # multi-line declaration are skipped regardless of how they
             # look in isolation — e.g. `    = std::vector<int>;` after a
             # two-line `using value_type` alias must not count as a member.
+            # Only `class` bodies are penalised: in C++ a `struct` has
+            # public access by default and public data members are a
+            # legitimate, intended usage (POD aggregate, value types,
+            # mixin tags). Treating them as a code-quality issue would
+            # penalise perfectly idiomatic C++.
             if prev_depth == 1 and access_per_line[idx] == "public" \
+                    and kind == "class" \
                     and idx not in continued_idxs:
                 if is_public_member_var(line):
                     pub_findings.append(Finding(