chore: Clean up selector playground code

[jennifer-shehane]

• Closes https://github.com/cypress-io/cypress-services/issues/10605

Additional details

We do intend to add some of this functionality back, if we do - we can look back here for any of the code.

I have a hard time thinking any of this will really be reusable though given that the updates would have highlighting logic moving to our new logic and the unique-selector moving to our new logic (which is in the Cloud).

Steps to test

How has the user experience changed?

Right now the Selector Playground is mistakenly available in CT testing actually (since it is just using the studio disabled prop to show or not show). This should remove that.

PR Tasks

• Have tests been added/updated?
• Has a PR for user-facing changes been opened in cypress-documentation?
• Have API changes been updated in the type definitions?

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Note

Removes Selector Playground UI/store and highlight logic across the app, updating runner headers, AUT iframe, locales, styles, and tests accordingly.

• App Runner (Open/Run Mode):
  • Remove Selector Playground button/UI from SpecRunnerHeaderOpenMode.vue and related logic; delete selector-playground components and store; strip playground handling from unifiedRunner.ts, utils.ts, and Runner.vue.
  • Simplify EventManager and aut-iframe.ts by removing selector playground/highlight generation APIs and dependencies.
• Types/Docs:
  • Update Cypress.ElementSelector JSDoc to reference Cypress Studio and cy.prompt(); minor changelog link cleanup.
• Tests:
  • Delete Selector Playground component/e2e tests and sample project; remove assertions about playground-activator; adjust runner header tests.
• Styles/Locales:
  • Remove selector playground-specific styles/import exclusions and locale strings.
• Infra:
  • Drop selector playground references from init paths (index.ts, CT support mocks).

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[cypress]

cypress    Run #67050

Run Properties:   Passed #67050  •  b923efc93a: Remove some more relevant portions of code

Project	cypress
Branch Review	remove-selector-playground-code
Run status	Passed #67050
Run duration	19m 36s
Commit	b923efc93a: Remove some more relevant portions of code
Committer	Jennifer Shehane
View all properties for this run ↗︎

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Test results
Failures	0
Flaky	12
Pending	1097
Skipped	4
Passing	26507
View all changes introduced in this branch ↗︎

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Warning

Partial Report: The results for the Application Quality reports may be incomplete.

UI Coverage  45.29%
Untested elements	181
Tested elements	154

Accessibility  97.97%
Failed rules	4 critical   8 serious   2 moderate   2 minor
Failed elements	101