feat: workspace frontend integration (PR-4)

- Add workspace_id parameter to createInstance API client
- Wire WorkspacesPage 'Start Tool' modal to createInstance + startInstance
- Pass workspace_id when creating instance from workspace page
- TypeScript + eslint clean

apps/web/src/api/sessions.ts

@@ -54,13 +54,15 @@ export async function createInstance(
   branch?: string,
   newBranch?: string,
   configProfileId?: string,
-  sshKeyIds?: string[]
+  sshKeyIds?: string[],
+  workspaceId?: string
 ): Promise<ToolInstance> {
   const response = await apiClient.post(
     `/projects/${projectId}/repositories/${repoId}/instances`,
     {
       tool_type_id: toolTypeId,
       display_name: displayName,
+      workspace_id: workspaceId || undefined,
       clone_mode: cloneMode || "mount",
       branch: branch || undefined,
       new_branch: newBranch || undefined,