chore: clean up redundant access specifiers in hnsw_sparse

[SYaoJun]

Hi zvec team, I read the code in the hnsw_sparse directory and found some clang-tidy warnings about redundant class access specifiers (public and private). Would you consider adding the readability-redundant-access-specifiers check to .clang-tidy?

[SYaoJun]

Hi @Cuiyus, I'm encountering a CI failure related to running Ruff Linter. Do you know how to fix it?

[Cuiyus]

Thank you for your contribution. Zvec also plans to incorporate clang-tidy checks. The "readability-redundant-access-specifiers" issue you mentioned will be taken into consideration.

Furthermore, for the failures caused by the Ruff Linter check, I did not observe them in the current PR's CI. They should have been fixed in the commit #59.

[Cuiyus]

We have grouped the private member functions in one section and the private data members in another section. This arrangement is in line with the current code style design of zvec. We believe that this code organization method will enhance the readability and maintainability of the code.

[SYaoJun]

We have grouped the private member functions in one section and the private data members in another section. This arrangement is in line with the current code style design of zvec. We believe that this code organization method will enhance the readability and maintainability of the code.

OK. Glad to confirm your design intent; I'll close this PR.