docs: add universal context capsule

AGENTS.md

@@ -0,0 +1,21 @@
+# JKTV AI Working Agreement
+
+Read `context/boot.md` and `context/capsule.json` before changing the product.
+Then read the smallest relevant document and implementation module.
+
+## Source Boundaries
+
+- JKTV owns the CS2 team data model, import pipeline, player and match views,
+  roster analysis and self-hosted application source.
+- JOps owns shared edge, deployment observation and platform authentication
+  facts.
+- Imported match files, runtime databases, tokens and user content remain
+  outside Git.
+
+## Change Protocol
+
+1. Preserve L1 raw, L2 normalized and L3 product-data boundaries.
+2. Keep derived statistics reproducible from source match data.
+3. Reject write operations without server-side authorization and CSRF checks.
+4. Update product or data architecture documentation with contract changes.
+5. Run `make context-check` and `make check` before committing.