Optimize provider scheduler database hotspots

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

@@ -0,0 +1,16 @@
+CREATE INDEX IF NOT EXISTS idx_provider_api_keys_provider_active_priority_id
+    ON provider_api_keys (provider_id, is_active, internal_priority, id);
+
+CREATE INDEX IF NOT EXISTS pool_member_scores_scheduler_account_rank_idx
+    ON pool_member_scores (
+        pool_kind,
+        pool_id,
+        capability,
+        scope_kind,
+        scope_id,
+        hard_state,
+        score DESC,
+        last_ranked_at DESC,
+        member_id,
+        id
+    );