feat: Implement legacy fallback for quota warnings and update messages before TBB

[ethanyhou]

This PR is a fallback of: #186

Test:

1. login with eclipse-pro account.
2. When no quota, Copilot should auto switch to the fallback model:

[Copilot]

Pull request overview

This PR adds legacy pre-TBB quota fallback handling and extends the model picker/chat request flow to support selectable reasoning effort metadata.

Changes:

• Adds reasoning-effort protocol fields, preference persistence, picker/hover UI, and per-turn rendering/persistence.
• Updates chat requests to send modelInfo.reasoningEffort.
• Restores legacy 402 quota fallback messaging/replay behavior when token-based billing is not enabled.

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 1 comment.

Show a summary per file

File	Description
com.microsoft.copilot.eclipse.ui/src/com/microsoft/copilot/eclipse/ui/utils/ModelUtils.java	Adds reasoning-effort helpers and updates model suffix formatting.
com.microsoft.copilot.eclipse.ui/src/com/microsoft/copilot/eclipse/ui/swt/ModelHoverContentProvider.java	Adds interactive thinking-effort rows to model hover content.
com.microsoft.copilot.eclipse.ui/src/com/microsoft/copilot/eclipse/ui/swt/ItemController.java	Extends row hover/focus behavior for reusable popup rows.
com.microsoft.copilot.eclipse.ui/src/com/microsoft/copilot/eclipse/ui/swt/IDropdownItemHoverProvider.java	Adds a close callback for interactive hover content.
com.microsoft.copilot.eclipse.ui/src/com/microsoft/copilot/eclipse/ui/swt/DropdownPopup.java	Keeps hover popups open for interaction and supports hover-triggered close.
com.microsoft.copilot.eclipse.ui/src/com/microsoft/copilot/eclipse/ui/swt/DropdownItem.java	Adds optional selected button-face labels.
com.microsoft.copilot.eclipse.ui/src/com/microsoft/copilot/eclipse/ui/swt/DropdownButton.java	Uses selected labels and updates width when items change.
com.microsoft.copilot.eclipse.ui/src/com/microsoft/copilot/eclipse/ui/i18n/messages.properties	Adds localized reasoning-effort labels/descriptions.
com.microsoft.copilot.eclipse.ui/src/com/microsoft/copilot/eclipse/ui/i18n/Messages.java	Adds NLS fields for new messages.
com.microsoft.copilot.eclipse.ui/src/com/microsoft/copilot/eclipse/ui/chat/services/ModelService.java	Persists reasoning-effort choices and rebuilds model picker items.
com.microsoft.copilot.eclipse.ui/src/com/microsoft/copilot/eclipse/ui/chat/ModelPickerGroupsBuilder.java	Includes effective reasoning effort in model item suffix/selected label.
com.microsoft.copilot.eclipse.ui/src/com/microsoft/copilot/eclipse/ui/chat/CopilotTurnWidget.java	Renders reasoning effort in model footer text.
com.microsoft.copilot.eclipse.ui/src/com/microsoft/copilot/eclipse/ui/chat/ChatView.java	Sends, renders, and persists per-turn reasoning effort.
com.microsoft.copilot.eclipse.ui/src/com/microsoft/copilot/eclipse/ui/chat/ChatContentViewer.java	Adds legacy quota warning fallback and replay behavior.
com.microsoft.copilot.eclipse.core/src/com/microsoft/copilot/eclipse/core/persistence/CopilotTurnData.java	Persists reasoning effort in reply data.
com.microsoft.copilot.eclipse.core/src/com/microsoft/copilot/eclipse/core/persistence/ConversationPersistenceManager.java	Stores reasoning effort with model info.
com.microsoft.copilot.eclipse.core/src/com/microsoft/copilot/eclipse/core/lsp/protocol/ModelInfo.java	Adds model metadata payload for chat protocol requests.
com.microsoft.copilot.eclipse.core/src/com/microsoft/copilot/eclipse/core/lsp/protocol/CopilotModel.java	Adds reasoning-effort capability metadata and model key helper.
com.microsoft.copilot.eclipse.core/src/com/microsoft/copilot/eclipse/core/lsp/protocol/ConversationTurnParams.java	Adds modelInfo to turn params.
com.microsoft.copilot.eclipse.core/src/com/microsoft/copilot/eclipse/core/lsp/protocol/ConversationCreateParams.java	Adds modelInfo to create params.
com.microsoft.copilot.eclipse.core/src/com/microsoft/copilot/eclipse/core/lsp/CopilotLanguageServerConnection.java	Sends modelInfo.reasoningEffort on chat requests.
com.microsoft.copilot.eclipse.core/src/com/microsoft/copilot/eclipse/core/chat/UserPreference.java	Stores reasoning-effort selections per model.

Comments suppressed due to low confidence (1)

com.microsoft.copilot.eclipse.ui/src/com/microsoft/copilot/eclipse/ui/swt/ModelHoverContentProvider.java:174

• This hover section also ignores the new supportsReasoningEffortLevel() gate and will render selectable effort rows whenever the raw list has more than one entry, even if the server says the model/endpoint does not support effort selection. Please base this on ModelUtils.getSupportedReasoningEfforts(model) after that helper checks the support flag, or explicitly require supports.supportsReasoningEffortLevel() here.

    sectionLayout.marginHeight = 0;
    sectionLayout.verticalSpacing = 2;
    ((GridData) section.getLayoutData()).verticalIndent = SECTION_SPACING;