Add AGENTS.md with Cursor Cloud development instructions

[pingles]

Summary

Adds AGENTS.md with development environment instructions for Cursor Cloud agents.

What's included

• Overview of the monorepo structure (bandit-core, bandit-simulate, bandit-ring)
• Prerequisites (JDK 11, Leiningen 2.x, JAVA_HOME)
• Key commands table for install, test, run
• Gotchas discovered during setup (outdated README command, JVM GC flag deprecation, port argument requirement)

Environment verification

All services were verified working:

• Tests: 55 tests passing across all sub-projects via lein sub do expectations, test
• Web app: bandit-ring running on port 8080 with both adverts and ranking examples functioning
• Simulation: bandit-simulate producing CSV output correctly

Demo

bandit_app_demo.mp4

Multi-armed bandit optimization demo showing ranking reordering and ad click-through tracking.

Bandit state after clicking advert

_{To show artifacts inline, enable in settings.}