Add always-on Cursor AGENTS context rule (#4544)

## Summary
- add `.cursor/rules/00-agent-context.mdc` as an always-applied Cursor
rule
- instruct agents to load `/AGENTS.md` when present and use nearest
`AGENTS.md` as override
- keep AGENT context active for routine and larger tasks

## Test plan
- [x] Confirmed the new file is tracked by git
- [x] Reviewed rule front matter for `alwaysApply: true` and `globs:
["**/*"]`

Made with [Cursor](https://cursor.com)

---------

Co-authored-by: Cursor <cursoragent@cursor.com>

Author: simonfaltum

.cursor/rules/00-agents-context.mdc

@@ -0,0 +1,13 @@
+---
+description: Always load AGENTS.md context first
+alwaysApply: true
+globs:
+  - "**/*"
+---
+
+Always apply AGENTS context before taking actions.
+
+1. If `/AGENTS.md` exists, read and follow it for every task in this workspace.
+2. When working in a subdirectory, check for a closer `AGENTS.md` in that path and follow it as an override.
+3. If multiple `AGENTS.md` files apply and conflict, the most specific (closest) one wins.
+4. Keep these instructions active even for small or routine requests.