docs: update RBAC viewer role description after #3187 guards (#3193)

PR #3187 added requireRole() RBAC guards to templates and tools
endpoints. Updated enterprise.md viewer role description to reflect
that viewer can now also read templates and tools (not just sessions
and metrics).

api-reference.md already had correct RBAC roles — no changes needed.

Author: OneStepAt4time

docs/enterprise.md

@@ -29,7 +29,7 @@ Aegis supports multiple API keys with role-based access control:
 
 | Role | Permissions |
 |------|-------------|
-| `viewer` | Read-only access to sessions and metrics |
+| `viewer` | Read-only access to sessions, templates, tools, and metrics |
 | `operator` | Read + write sessions, approve permissions |
 | `admin` | Full access including key management |