added ability to check shared devices

deploy/migrations/20260714003130_authorizations_device_fingerprint_index.down.sql

@@ -0,0 +1 @@
+DROP INDEX IF EXISTS idx_authorizations_device_fingerprint;

deploy/migrations/20260714003130_authorizations_device_fingerprint_index.up.sql

@@ -0,0 +1,10 @@
+-- Supports the admin console's "accounts sharing a device" report, which
+-- groups authorizations by (device_model, system_version, platform, ip) and
+-- looks for groups spanning more than one distinct user_id. Without this
+-- index that GROUP BY is a full sequential scan of authorizations, a table
+-- that grows roughly with active-session count and is never pruned except on
+-- explicit revoke.
+
+CREATE INDEX idx_authorizations_device_fingerprint
+  ON public.authorizations (device_model, system_version, platform, ip)
+  WHERE device_model <> '';