write input file contents at the top of each output per-problem

[markleader]

Summary

Echo each problem's original input block at the top of the corresponding legacy CLI .out section, independent of problem type.

Changes

• Added ProblemDB%raw_input to preserve the original per-problem input text during parsing.
• Updated read_problem to capture each problem block's raw input while keeping existing parsing behavior unchanged.
• Added a main.f90 output helper that writes the stored input block before equilibrium, rocket, shock, and detonation output sections.

Testing

• Ran focused CLI checks:
  • ./build-dev/source/cea test/main_interface/example1
  • ./build-dev/source/cea test/main_interface/example8
  • ./build-dev/source/cea test/main_interface/example7
  • ./build-dev/source/cea test/main_interface/example6
• Ran regression script: python test/main_interface/test_main.py
  • Result: 13/14 tests passed; existing example11 mismatch remained unchanged

Compatibility / Numerical behavior

• No expected changes to numerical results
• Expected changes (explain and provide validation)