feat: restrict backup archive download to primary admin and hide admin-hidden projects from other admins

- Add `get_admin_uids()` and `get_primary_admin_uid()` to database.py for resolving the earliest-created admin
- Modify `can_view_project()` in content.py so a project hidden by an admin is invisible to other admins (both web UI and REST API)
- Update `_download_url()` and `_backup_payload()` in admin/backups.py to accept a `can_download` flag, gating the download endpoint with `is_primary_admin()`
- Remove `role` from `_user_facts()` in docs_live.py to avoid leaking admin status in live docs
- Update doc summaries in docs_api.py to reflect the new admin-visibility and backup-download semantics

devplacepy/services/openai_gateway/service.py

@@ -267,6 +267,15 @@ class GatewayService(BaseService):
             help="Fallback only; used when the embeddings upstream returns no native cost.",
             group="Pricing",
         ),
+        ConfigField(
+            "gateway_rsearch_cost_per_call",
+            "rsearch cost / call ($)",
+            type="float",
+            default=config.RSEARCH_COST_PER_CALL_DEFAULT,
+            minimum=0,
+            help="Flat cost attributed to each external rsearch call (web search / AI answer / chat / image describe), recorded under backend 'rsearch' so external AI spend appears in AI usage.",
+            group="Pricing",
+        ),
         ConfigField(
             "gateway_max_retries",
             "Max retries",