Follow coding style guidelines

The style lead wants this module to match our C++ style guide. Reformat ai/pathfinder.cpp to follow the guide: use four-space indentation, place opening braces on the same line as function declarations, prefer explicit auto only for iterators, wrap lines at 100 characters, and add a short header comment with author and date. Do not change algorithm logic or function signatures.

Before I send the style changes to the team, make them easy to review. Highlight the visible style diffs: indentation and brace placement, renamed local variables to match lower_snake_case, and the places where line wrapping moved code. Note any substantive changes that could affect readability (for example, added explicit types).

A reviewer just refused my patch because ai/pathfinder.cpp doesn't follow the style guide; they demanded many tiny renames and rewraps. I agree some are cosmetic but I'm short on time. Which style violations are important to fix now to unblock the review, and which can safely wait for a follow-up cleanup?

Across many PRs, reviewers spend hours on formatting and naming nitpicks that don't affect correctness. It slows merges and frustrates engineers. Which little process change or tooling setup will reclaim review time and keep code readable without a parade of style-only commits?