- Add token_info_t structure with type, value, and source location
  tracking
- Add source_location_t for precise error reporting (line, column,
  filename)
- Add token_pool_t for freelist-based memory reuse pattern
- Add token_buffer_t for 8-token circular buffer lookahead capability

This commit implements token_pool_alloc()/free() with freelist pattern
for memory reuse and adds circular buffer implementation for 8-token
lookahead capability. Then, it implements source location tracking via
tokenization process and adds enhanced error reporting with
file:line:column format.

Memory management benefits:
- Each reused token saves ~284 bytes of memory
- Fixed overhead < 2.5KB for buffer and pool structures
- Zero memory leaks through arena-based allocation