feat(web): pick reviewers when editing policies.cedar (#2165)

* feat(web): pick reviewers when editing policies.cedar

Add a BlobEditor member multi-select that rewrites the matching path's `to [...]` list, mirroring MegaCedarAdminPicker without a new API.

* feat(identity): persist mono actors as campsite_user_id

Replace username-keyed collaboration storage with Campsite public ids,
keep github_login for Cedar/display, and resolve CL UI members by id so
handles no longer render as opaque ids.

* fix clippy

Author: benjamin-747

.gitignore

@@ -58,6 +58,9 @@ orion-server/docker-compose.override.yml
 # local dev environment
 /scripts/dev/.env
 
+# local mono config override (preferred over config/config.toml when present)
+/config/config.local.toml
+
 .buildx-cache
 
 # Claude Code configuration and cache