Remove Stagehand context accessors

[miguelg719]

why

With consumers migrated, keeping Stagehand context aliases would preserve an API we do not want to support in v4.

what changed

Removes Stagehand context accessors from TypeScript, Python, and Go and adds API regression guards plus updated parity expectations.

No changeset: this targets the unreleased v4 API.

test plan

• TypeScript SDK build and unit tests
• Full Python SDK suite
• Go SDK suite
• Cross-language parity tests

---

Summary by cubic

Removed Stagehand context accessors across TypeScript, Python, and Go. Only stagehand.browser.context remains, with new public API tests and parity rules to prevent reintroducing the legacy accessor.

• Migration
  • TypeScript: change stagehand.context to stagehand.browser.context.
  • Python: change stagehand.context to stagehand.browser.context.
  • Go: change Stagehand.Context() to Stagehand.Browser().Context().

Linked Linear: STG-2763.

^{Written for commit c950fc7. Summary will update on new commits.}

[changeset-bot]

⚠️ No Changeset found

Latest commit: c950fc7

Merging this PR will not cause a version bump for any packages. If these changes should not result in a new version, you're good to go. If these changes should result in a version bump, you need to add a changeset.

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[cubic-dev-ai]

cubic analysis

All reported issues were addressed

Linked issue analysis

Linked issue: STG-2763: Change stagehand.context to browser.context

Status	Acceptance criteria	Notes
✅	Remove Stagehand.Context() method from the Go SDK API	The Stagehand.Context() method was deleted from packages/sdk-go/stagehand.go; related tests now reference the browser handle.
✅	Replace uses of Stagehand.Context() with Browser().Context() in Go tests/code	Live/test code now calls client.Browser().Context() and error messages updated accordingly.
✅	Add Go unit test asserting Stagehand does not expose Context	A test was added that fails if Stagehand has a Context method.
✅	Remove Stagehand.context property in Python and add a test ensuring it's not exposed	The context property was removed from the Python Stagehand class and a test asserts Stagehand has no 'context' attribute.
✅	Remove Stagehand.context getter in TypeScript and add tests asserting it is not published	The getter was removed and tests now assert 'context' is not present on Stagehand.prototype and via type checks.
✅	Update docs/README to indicate context is on the browser handle	README text was changed to state that Stagehand exposes context on the browser handle.
✅	Update cross-language parity expectations to no longer require Stagehand.Context	The parity rule no longer includes 'Context' in the Stagehand accessor set.

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