chore: rename CLAUDE.md to AGENTS.md and Justfile to justfile (#63)

Author: lesnik512

CLAUDE.md AGENTS.mdCLAUDE.md renamed to AGENTS.md

@@ -1,4 +1,4 @@
-# CLAUDE.md
+# AGENTS.md
 
 This file provides guidance to Claude Code (claude.ai/code) when working with code in this repository.
 
@@ -8,7 +8,7 @@ Python 3.14 async REST API. FastAPI + SQLAlchemy 2 (async) + PostgreSQL + Alembi
 
 ## Common commands
 
-The development workflow runs inside Docker via `just` (`just --list` / read the `Justfile` for the full recipe list). The `application` service mounts the repo and depends on a `db` Postgres service. Bare `just` runs the default pipeline (install + lint + build + test).
+The development workflow runs inside Docker via `just` (`just --list` / read the `justfile` for the full recipe list). The `application` service mounts the repo and depends on a `db` Postgres service. Bare `just` runs the default pipeline (install + lint + build + test).
 
 Things the recipe names don't make obvious: