add REPO_POLICIES.md, rename CLAUDE.md to AGENTS.md, deduplicate

- Add REPO_POLICIES.md from the standard template (sneak/prompts)
- Rename CLAUDE.md to AGENTS.md with agent-specific workflow instructions
- Move policy-like rules (git add, make targets, etc.) to REPO_POLICIES.md
- Add reference to REPO_POLICIES.md in README Participation section
- Run make fmt (prettier formatting on markdown files)

AGENTS.md

@@ -0,0 +1,29 @@
+# Agent Instructions
+
+Read `REPO_POLICIES.md` before making any changes. It is the authoritative
+source for coding standards, formatting, linting, and workflow rules.
+
+## Workflow
+
+- When fixing a bug, write a failing test FIRST. Only after the test fails,
+  write the code to fix the bug. Then ensure the test passes. Leave the test in
+  place and commit it with the bugfix. Don't run shell commands to test bugfixes
+  or reproduce bugs. Write tests!
+
+- After each change, run `make fmt`, then `make test`, then `make lint`. Fix any
+  failures before committing.
+
+- After each change, commit only the files you've changed. Push after committing.
+
+## Attribution
+
+- Never mention Claude, Anthropic, or any AI/LLM tooling in commit messages. Do
+  not use attribution.
+
+## Repository-Specific Notes
+
+- This is a Go library + CLI tool for generating `.mf` manifest files.
+- The proto definition is in `mfer/mf.proto`; generated `.pb.go` files are
+  committed (required for `go get` compatibility).
+- The format specification is in `FORMAT.md`.
+- See `TODO.md` for the 1.0 implementation plan and open design questions.