Fix refcount leak, unaligned reads, and YEAR type mismatch in accel.c

- Fix Py_None refcount leak in load_rowdat_1: remove pre-switch INCREF,
  move INCREF before PyTuple_SetItem in each null branch, and remove the
  post-SetItem INCREF that was leaking a reference on every null value
- Replace unaligned pointer dereferences (*(type*)data) with memcpy in
  load_rowdat_1 and load_rowdat_1_numpy to avoid undefined behavior on
  alignment-sensitive platforms (ARM, WASM)
- Fix YEAR type signed/unsigned mismatch in dump_rowdat_1 and
  call_function_accel output paths: use uint16_t/PyLong_AsUnsignedLong
  to match the unsigned input path in load_rowdat_1

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Author: kesmit13