Docs described a "Context Files" feature that does not exist

[martsokha]

The documentation described a Context Files feature — workspace-scoped encrypted JSON files providing detection context (custom entity definitions, terminology, redaction rules), with a CRUD/multipart-upload API surface — but no such thing exists in the code:

• No ContextFile / context_files model, table (schema.rs), handler, or route.
• The closest real feature is workspace policies (workspace_policies table, crates/nvisy-server/src/handler/policies.rs, elide_pipeline::policy::PolicyDefinition), which already carry the per-workspace detection configuration the docs attributed to "Context Files".

Action taken

Removed the stale references while updating the docs for the NATS→S3 storage migration:

• docs/ARCHITECTURE.md — resource-type entry + API-surface table row
• docs/INTELLIGENCE.md — the ### Context Files section + the job-dispatch step

Decision needed

One of:

1. Nothing to build — "Context Files" was an earlier name for what shipped as Policies; the removal is sufficient. (Optionally document Policies in the API-surface table, which currently omits them.)
2. Build it — Context Files are a distinct, still-wanted feature (uploadable context blobs separate from policies); this issue tracks implementing them.

Please confirm which, so the docs and/or backlog reflect reality.

Filed while refreshing docs for the S3 blob-storage migration (PR #268).