Basic git hooks

[ulgens]

A soft entry for automated format & lint flows.

Fixes trailing whitespaces and end-of-file issues.

[dylanroscover]

workflow itself is great and i want to land it — but the fixers need an exclude: for the TD-written trees (dev/embody/, dev/specimen_lab/, specimens/). two examples from this diff:

• the missing final newlines are just how TD serializes DATs. the fixer adds them, TD strips them on next save, CI goes red forever
• divergent_defaults.tsv: 276 rows end in a tab because the 4th column is legitimately empty — the hook deleted those cells, TD will put them back

add the exclude + drop the fix commits for those paths and this merges as-is. (wrote CONTRIBUTING.md to document all this — your PRs prompted it tbh)

[ulgens]

the missing final newlines are just how TD serializes DATs. the fixer adds them, TD strips them on next save, CI goes red forever

I'll check why TD is doing that, and if there are any ways to fix that behaviour.

That being said, with a git hook setup, fixer would apply these fixes before the commit is made so ideally (developers should have the hooks initialized on their locals) those un-fixed files wouldn't reach the CI.