Validate JSON Lines input before chunk access

[SRO-SA]

Fixes #2

Summary:

• Validates JSON Lines input before any data access or chunk dereference.
• Rejects NULL input.data with non-zero input.size.
• Rejects zero chunkCount and inconsistent chunk metadata.
• Rejects NULL chunk pointers when the corresponding chunk size is non-zero.
• Updates the parse_json_lines header prototype to use cuJSONLinesInput, matching the implementation.

Testing:

• I could not run the ASAN reproducer locally because my laptop does not have CUDA access.
• I reviewed the entry-point validation and chunk access path manually.
• Please rerun the ASAN reproducer from the issue to confirm the NULL pointer dereference is resolved.