Rework the research front door - #1

What changed

• lead the README with M3, X2, and governed-continuity results
• add run commands and related links
• move the process warning into a linked retrospective
• add an MIT license and Linguist classifications
• scrub two public local-path leaks

Why

Cold reviewers should see the strongest results before the process history. Public files should not expose machine-local paths.

Checks

• make m3-test
• make x2-test
• git diff --check

The full document-route check still reports 15 pre-existing cross-repo routes outside this patch.