Persist chat tips disablement across workspaces

[Copilot]

Chat tips were disabled per workspace, causing them to reappear when opening another workspace. This change treats disablement as a user-level choice.

• Configuration scope
  • Mark chat.tips.enabled as application-scoped so it is shared across workspaces.
• Disable action
  • Persist disablement using the application configuration target.
• Coverage
  • Add a unit test that asserts disableTips() writes to the application target.

Example:

await this._configurationService.updateValue('chat.tips.enabled', false, ConfigurationTarget.APPLICATION);

Original prompt

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This section details on the original issue you should resolve

<issue_title>Disabling Chat tips should be preserved across workspaces</issue_title>
<issue_description>1. Open workspace, see Chat tips
2. Click on X to no longer show tips
3. Open another workspace. See chat tips again 🐛

Hiding tips should be preserved across workspaces (it is a user choice, not a workspace choice)

cc @roblourens </issue_description>

Comments on the Issue (you are @copilot in this section)

• Fixes Disabling Chat tips should be preserved across workspaces #295557

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[Copilot]

Pull request overview

This PR fixes an issue where disabling chat tips was only persisted per-workspace, causing them to reappear when switching workspaces. The fix treats tip disablement as a user-level preference by using application-scoped configuration.

Changes:

• Mark chat.tips.enabled configuration as application-scoped to share setting across all workspaces
• Update disableTips() to persist the setting to ConfigurationTarget.APPLICATION instead of default target
• Add unit test to verify that disablement writes to the application configuration target

Reviewed changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated no comments.

File	Description
src/vs/workbench/contrib/chat/browser/chat.contribution.ts	Add scope: ConfigurationScope.APPLICATION to chat.tips.enabled setting definition
src/vs/workbench/contrib/chat/browser/chatTipService.ts	Update disableTips() to use ConfigurationTarget.APPLICATION when persisting the setting
src/vs/workbench/contrib/chat/test/browser/chatTipService.test.ts	Add TrackingConfigurationService test helper and new test to verify application target is used