[Dependency] Method-layer lateral coupling `pw ↔ lcao`

[Critsium-xy]

Describe the Code Quality Issue

• Symptom: pw → lcao (dftu.h, spin_constrain.h, module_ri/*) and lcao → pw (structure_factor.h, onsite_proj.h, forces.h, …) depend on each other.
• Fix:
  • components shared by both sides — dftu, deltaspin(spin_constrain), RI: if basis-independent, sink into source_base / a standalone module;
  • lift hybrid-method logic like LCAO-in-PW (lcaopw) up into source_esolver (esolver_ks_lcaopw already lives there).
• Acceptance: pw and lcao no longer include each other.

Additional Context

No response

Task list for Issue attackers (only for developers)

• Identify the specific code file or section with the code quality issue.
• Investigate the issue and determine the root cause.
• Research best practices and potential solutions for the identified issue.
• Refactor the code to improve code quality, following the suggested solution.
• Ensure the refactored code adheres to the project's coding standards.
• Test the refactored code to ensure it functions as expected.
• Update any relevant documentation, if necessary.
• Submit a pull request with the refactored code and a description of the changes made.