chore(release): v1.42.0 (#4715)

<!-- auto-release-pr -->
This PR prepares `v1.42.0`.

- Code difference since last tag:
[v1.41.1...561214639](https://github.com/inngest/inngest/compare/v1.41.1...561214639fa444db60d3dbe19cf10278343ff455)
- Previous tag: `v1.41.1`
- Source branch: `release/next`
- Base branch: `main`

### Additional Release Notes
<!-- release-note:manual-start -->
<!-- release-note:manual-end -->

### Additional Migration Notes
<!-- migration-note:manual-start -->
<!-- migration-note:manual-end -->

## Final Release Page Preview

> This generated preview is the release notes body that will be
published to the GitHub Release page. It intentionally includes the
additional notes above, followed by collected PR notes and the
changelog.

<details open>
<summary>Rendered release notes body</summary>

<!-- release-note:preview-start -->
## Release Notes

- [#4697](https://github.com/inngest/inngest/pull/4697)
feat(improvement): Add-scores-and-experiments-empty-states-to-dev-server

The dev server now includes Scores and Experiments pages (AI section,
beta) showing how to get started with `step.score()` and
`group.experiment()`. Data for these features is displayed in Inngest
Cloud after deploying; the dev server pages let you register interest in
local support.

- [#4718](https://github.com/inngest/inngest/pull/4718) fix(traces):
scope span self-join by run_id

Fixed the runs list hanging on large Postgres deployments when
`deferredFrom`/`isDeferred` was selected. No migration or manual index
needed.

- [#4720](https://github.com/inngest/inngest/pull/4720) feat: Surface
event scheduling in the dashboard

- Surface scheduled at in the dashboard's run's page iff the event is
scheduled in the future

- [#4721](https://github.com/inngest/inngest/pull/4721) refactor(runs):
remove legacy tokens from run output header

Removed Model/token values parsed from `step.run` output in favor of a
nudge towards the better AI metadata setup.

- [#4724](https://github.com/inngest/inngest/pull/4724) feat(api): add
v2 send event endpoint

  Added a send event endpoint to the v2 rest api, cli and mcp.

  `POST` `/v2/events`

  ```
  inngest api --prod send-event \
    --name "app/user.created" \
    --data '{"userId":"user_123","email":"ada@example.com"}' \
    --id "user-created-user_123"
  ```

- [#4737](https://github.com/inngest/inngest/pull/4737) fix(traces):
hide expand/collapse all when there is nothing to toggle

Expand and contract buttons in the trace viewer are hidden when they
will not change what's displayed

- [#4744](https://github.com/inngest/inngest/pull/4744) feat(ui): adding
a concurrency color in the graph

Changing the Overview and the Functions page to show concurrency limits
being reached in UI.

- [#4749](https://github.com/inngest/inngest/pull/4749) fix(batch):
propagate timeout scheduling errors so source events retry

Fixed an issue where transient scheduling failures could prevent a new
batch's timeout job from being enqueued, causing the batch to remain
pending past its configured timeout until it reached its batch limit.

## Migration Notes

- [#4697](https://github.com/inngest/inngest/pull/4697)
feat(improvement): Add-scores-and-experiments-empty-states-to-dev-server

  🤖 Generated with [Claude Code](https://claude.com/claude-code)

  https://claude.ai/code/session_01QgjtSu6eF6j3bc8GWC6buN

- [#4722](https://github.com/inngest/inngest/pull/4722) chore(queue):
remove system queue migrations

  None

  ## Validation

- `go test -count=1 ./pkg/execution/queue
./pkg/execution/state/redis_state ./pkg/execution/executor
./pkg/execution/deletion ./tests/execution/queue`
  - `git diff --check`

- [#4723](https://github.com/inngest/inngest/pull/4723) feat(queue): let
custom scanners declare roles

  None

  ## Validation

  - `go test -count=1 ./pkg/execution/queue`

- [#4726](https://github.com/inngest/inngest/pull/4726) fix(queue):
preserve sentinel shard selection errors

  None

  ## Checks

  - `go test -count=1 ./pkg/execution/queue`
  - `git diff --check`

- [#4753](https://github.com/inngest/inngest/pull/4753) fix(ui): adding
legend for concurrency limit on hover

<img width="321" height="384" alt="image"
src="https://github.com/user-attachments/assets/4f9aed1d-25ed-4749-8d3e-82d3c214e26e"
/>

## Changelog

### 🚀 Features

- Add SDK feature observations (#4700)
- *(connect)* Adding support for connect HA (#4714)
- *(queue)* Let custom scanners declare roles (#4723)
- *(api)* Add v2 sandbox contracts (#4716)
- Surface event scheduling in the dashboard (#4720)
- *(ai metadata)* More robust AI model cost data (#4728)
- *(improvement)* Add-scores-and-experiments-empty-states-to-dev-server
(#4697)
- *(improvement)* Cloud MCP UI (#4729)
- *(ui-mcp)* Re-add MCP setup page (#4740)
- *(mcp)* Restore setup docs with public operations (#4748)
- *(ui)* Adding a concurrency color in the graph (#4744)
- *(api)* Add v2 send event endpoint (#4724)

### 🐛 Bug Fixes

- *(traces)* Scope span self-join by run_id (#4718)
- 64 bit linux download link for install.sh script (#4727)
- *(queue)* Preserve sentinel shard selection errors (#4726)
- Revert "feat(improvement): Cloud MCP UI (#4729)" (#4739)
- *(ui-mcp)* Revert MCP setup page redesign (#4745)
- *(redis-state)* Tolerate legacy idempotency tombstones (#4747)
- *(batch)* Propagate timeout scheduling errors so source events retry
(#4749)
- *(traces)* Hide expand/collapse all when there is nothing to toggle
(#4737)
- *(ui)* Adding legend for concurrency limit on hover (#4753)
- *(queue)* Disable constraint checks when key queues are disabled
(#4754)

### 🚜 Refactor

- *(runs)* Remove legacy tokens from run output header (#4721)
- *(queue)* Split queue reader capabilities (#4743)
- *(connect)* Remove the async ACK gateway -> executor (#4215)

### 📚 Documentation

- *(api)* Improve v2 app sync and insights docs (#4732)

### ⚙️ Miscellaneous Tasks

- *(queue)* Remove system queue migrations (#4722)
- *(batch)* Add more context to schedule batch execution (#4742)
- *(connect)* Adding run id to logs (#4698)
<!-- release-note:preview-end -->

</details>

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