feat: update chat component to use PluginSlot

[mraman-2U]

This pull request refactors the Chat component to remove feature-specific logic and enable a more generic, plugin-based architecture for learner tools. The changes simplify the component, delegate feature gating to plugins, and update related configuration and tests. The most important changes are:

Refactor to Plugin-Based Architecture:

• The Chat component (src/courseware/course/chat/Chat.jsx) is rewritten to remove all feature-specific logic (such as enrollment mode checks, exam state, and date validation) and instead renders a generic PluginSlot with minimal context (courseId, unitId, userId, isStaff, enrollmentMode). Plugins are now responsible for their own gating and requirements.
• The prop contentToolsEnabled is removed from Chat as it is no longer needed in the generic context.

Testing Overhaul:

• The Chat component test suite (src/courseware/course/chat/Chat.test.jsx) is completely rewritten. Tests now focus on verifying that PluginSlot is rendered when enabled, receives the correct props, and does not render when disabled. All previous feature-specific tests and mocks are removed, and a new strategy is used to mock and spy on PluginSlot props.

Openedx PR: openedx#1810

Configuration Updates:

• In .env.development, the BASE_URL and PORT are updated to use port 2010 instead of 2000, and the ENABLE_XPERT_AUDIT flag is added (previously FEATURE_ENABLE_CHAT_V2_ENDPOINT). [1] [2] [3]
• Minor whitespace cleanup in .env.

[Copilot]

Pull Request Overview

This pull request refactors the Chat component to adopt a plugin-based architecture, removing feature-specific logic and delegating gating responsibilities to plugins via PluginSlot. The changes simplify the component's responsibilities and update related configuration and tests.

Key changes:

• Replaced feature-specific rendering logic in Chat with a generic PluginSlot that provides minimal context (courseId, unitId, userId, isStaff, enrollmentMode)
• Rewrote test suite to focus on PluginSlot integration rather than feature-specific behavior
• Updated environment configuration to use port 2010 and replaced FEATURE_ENABLE_CHAT_V2_ENDPOINT with ENABLE_XPERT_AUDIT

Reviewed Changes

Copilot reviewed 4 out of 4 changed files in this pull request and generated no comments.

File	Description
src/courseware/course/chat/Chat.jsx	Simplified component to render PluginSlot instead of Xpert, removing all enrollment mode checks, exam state validation, and date logic
src/courseware/course/chat/Chat.test.jsx	Complete test rewrite focusing on PluginSlot rendering and prop passing rather than feature-specific visibility rules
.env.development	Updated port from 2000 to 2010 and replaced FEATURE_ENABLE_CHAT_V2_ENDPOINT with ENABLE_XPERT_AUDIT
.env	Removed FEATURE_ENABLE_CHAT_V2_ENDPOINT declaration

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