refactor: remove suggestions routes and related logic

This commit removes the suggestions routes and associated files from the server, streamlining the codebase. The `suggestionsModel` has been replaced with `ideationModel` across various components, including UI and service layers, to better reflect the updated functionality. Additionally, adjustments were made to ensure that the ideation service correctly utilizes the new model configuration.

- Deleted suggestions routes and their handlers.
- Updated references from `suggestionsModel` to `ideationModel` in settings and UI components.
- Refactored related logic in the ideation service to align with the new model structure.

apps/server/src/services/ideation-service.ts

@@ -688,9 +688,9 @@ export class IdeationService {
         existingWorkContext
       );
 
-      // Get model from phase settings with provider info (suggestionsModel)
+      // Get model from phase settings with provider info (ideationModel)
       const phaseResult = await getPhaseModelWithOverrides(
-        'suggestionsModel',
+        'ideationModel',
         this.settingsService,
         projectPath,
         '[IdeationService]'
@@ -730,6 +730,7 @@ export class IdeationService {
         // Disable all tools - we just want text generation, not codebase analysis
         allowedTools: [],
         abortController: new AbortController(),
+        readOnly: true, // Suggestions only need to return JSON, never write files
         claudeCompatibleProvider, // Pass provider for alternative endpoint configuration
         credentials, // Pass credentials for resolving 'credentials' apiKeySource
       };