Harden TIFF parsing/index bounds and split Python binding concerns from core library

[Copilot]

This change addresses three coupled issues: unsafe parsing/index assumptions in TIFF/log handling, tight Python-binding coupling in the C++ core API, and stale repository/build metadata. The update hardens input handling and frame/channel indexing while separating core library concerns from Python interop.

• Parsing and index hardening

  • Made channel metadata parsing resilient to malformed/partial header tokens (LUT, offsets, saved channels).
  • Replaced direct numeric conversions with guarded parsing paths for frame number/timestamp extraction.
  • Added explicit bounds validation for frame/channel mapping in setChannel, readFrame, writeFrame, tail, and saveTiffTail.
  • Added interpolation safeguards when nearest-index lookup returns invalid positions.

• Core/Python decoupling

  • Removed Python/carma types from the public core API (include/ScanImageTiff.h).
  • Core now exposes Armadillo-native signatures (e.g., readFrame -> arma::Mat<int16_t>, tail -> arma::Cube<int16_t> tuple).
  • Moved numpy/arma conversion to the pybind layer (src/ScanImageTiffPy.cpp) via binding lambdas.

• Build graph and stale metadata cleanup

  • Refactored CMake so the core shared library builds independently from Python bindings.
  • Added optional BUILD_PYTHON_BINDINGS flow with explicit dependency failure messaging.
  • Removed obsolete .gitmodules submodule metadata.
  • Removed stale test target source/link wiring tied to old Python-coupled structure.

// Binding layer now owns Python conversion boundary
.def("get_frame", [](twophoton::SITiffIO &self, int frame) {
  auto mat = self.readFrame(frame);      // core returns arma::Mat<int16_t>
  return carma::mat_to_arr(std::move(mat));
})