Optimize provider scheduler database hotspots

crates/aether-data/migrations/postgres/20260524000000_add_scheduler_hotspot_indexes.sql

@@ -0,0 +1,16 @@
+CREATE INDEX IF NOT EXISTS idx_provider_api_keys_provider_active_priority_id
+    ON public.provider_api_keys USING btree (provider_id, internal_priority, id)
+    WHERE is_active IS TRUE;
+
+CREATE INDEX IF NOT EXISTS pool_member_scores_scheduler_account_rank_idx
+    ON public.pool_member_scores USING btree (
+        pool_kind,
+        pool_id,
+        capability,
+        scope_kind,
+        score DESC,
+        last_ranked_at DESC NULLS LAST,
+        member_id,
+        id
+    )
+    WHERE scope_id IS NULL AND hard_state IN ('available', 'unknown');