fix: Cedar agent data update failure with git repo source

[Roshan931]

Fixes #506

Root cause

CedarClient drops policy-bundle data modules; non-JSON error bodies crash error handling

Changes

• CedarClient.set_policies now loads the bundle's data modules into cedar-agent (merging JSON entity lists into one PUT /v1/data, skipping non-list/invalid modules with a warning), and proxy_response_unless_invalid handles non-JSON error bodies so the real status code and body are surfaced instead of ContentTypeError. Added regression tests and documented repo-tracked Cedar entity files.

[netlify]

✅ Deploy Preview for opal-docs canceled.

Name	Link
🔨 Latest commit	9c2ac30
🔍 Latest deploy log	https://app.netlify.com/projects/opal-docs/deploys/6a88901dd6d29600097ab810