## Summary
Adds read methods to `RunStore` (`findRun`, `findRunOrThrow`,
`findRuns`) and routes every Postgres read of `TaskRun` through them,
mirroring how writes already go through the store. Behavior-preserving:
each relocated read keeps its exact query, field selection, and database
client (writer, replica, or transaction). This lets `TaskRun` reads be
retargeted to a different backing store later without touching call
sites.
Stacked on #3981 (the write adapter); that PR is the base of this one.
## Scope
In scope: the run engine, webapp services, presenters, and route
loaders. Three reads that pulled `TaskRun` in through a parent model's
relation `include` (alert delivery, batch results, attempt-dependency
cancellation) are decomposed to fetch the run(s) through the store and
stitch them back, since a relation include would not follow `TaskRun` to
a new table.
Left reading the existing table (out of scope): the legacy MarQS paths,
the legacy trigger idempotency read, and one raw-SQL recovery script
(commented for revisiting at cutover).
## Notes
Reads default to the read replica; callers pass the writer or a
transaction client wherever the original read did, so writer-vs-replica
behavior is unchanged.
## Summary
The Runs list now updates live without requiring a page refresh. Status
changes and other run fields are updated in place while runs are
executing.
When new runs matching the current filters are created, a "New runs
created" refresh button appears above the list.
Root runs now show a live child-run status breakdown directly in the
status tooltip.
### List live update
- Visible runs update in place while they are still running.
- A "New runs created" refresh button appears when new matching runs are
detected.
- Polling stops when all visible runs have finished and a refresh button
is already shown.
- Polling pauses when the browser tab is not visible.
- Runs list status updates and new-run detection share a single
runs/live polling path.
### Child-status tooltip
- Root run tooltips now display a breakdown of child run statuses.
- Child statuses are loaded when the tooltip opens (after a 400ms hover
delay).
- The tooltip stays up to date while child runs are still changing
state.
- Handles cases where child runs continue running after their parent run
has completed, or have not yet been created.
### Supporting changes
- Added hidden-tab awareness to polling.
- Added safeguards around polling inputs (`runIds` deduping and limits).
## Test plan
- [x] pnpm run typecheck --filter webapp passes
- [x] cd apps/webapp && pnpm run test
./test/presenters/mapRunToLiveFields.test.ts --run passes
- [x] cd apps/webapp && pnpm run test
./test/runsRepository.part2.test.ts --run -t "hasNewRuns" passes
### Manual smoke:
- [x] Active runs update without a page refresh.
- [x] A new matching run shows the refresh banner and the banner actions
work as expected.
- [x] Root run tooltips show live child-status updates and stop polling
once child runs settle.
---------
Co-authored-by: Ekaterina Bulatova <kathiekiwi@Ekaterinas-MacBook-Pro.local>
Chris Arderne