## Summary
The runs page's empty-state check (whether an environment has ever had a
run, which decides between the "getting started" and "no runs match your
filters" states) ran a `findFirst` against the Postgres `TaskRun` table.
This moves it to ClickHouse, the same store the runs list itself reads
from, so the check no longer queries `TaskRun`.
## Design
Only the runs list triggers the check now (via an `includeHasAnyRuns`
flag); the other presenters that reuse `NextRunListPresenter` (API,
schedule detail, waitpoint detail, error group) no longer issue it. When
the list is empty it runs `SELECT 1 FROM task_runs_v2 ... LIMIT 1`
filtered on the full `(organization_id, project_id, environment_id)`
sort-key prefix with a configurable `created_at` lower bound
(`RUN_LIST_HAS_RUNS_LOOKBACK_DAYS`, default 30), so it hits the primary
index and reads minimal granules.
Results are cached in a tiered memory + Redis SWR cache. Only positive
("has runs") results are cached, so an environment with no runs is
always re-checked and its first run shows up immediately.
Eric Allam
1a0198cc5e