feat: F024 global AI assistant — contextual decision intelligence drawer

Wires the existing "AI Assistent" button in the TopBar and adds a 420px
slide-in drawer with context-aware suggestions, message thread, loading
animation, and action cards requiring manual confirmation. Template-based
mock service returns German-language answers keyed by route + question
keywords — no real LLM calls, no invented facts.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

src/domain/assistant.ts

@@ -0,0 +1,38 @@
+import type { WorkspaceType } from './enums'
+
+export interface AssistantContext {
+  currentRoute: string
+  workspace: WorkspaceType | null
+  selectedEntityType?: string
+  selectedEntityId?: string
+  visibleScores?: Record<string, number>
+  visibleRisks?: string[]
+  visibleMissingData?: string[]
+  availableActions?: string[]
+  userRole: string
+  organizationId: string
+}
+
+export interface AssistantAction {
+  id: string
+  label: string
+  description: string
+  actionType: 'NAVIGATE' | 'OPEN_REVIEW' | 'ADD_TO_SHORTLIST' | 'REQUEST_DATA' | 'SEND_TO_REVIEW'
+  payload?: Record<string, unknown>
+}
+
+export interface AssistantMessage {
+  id: string
+  role: 'user' | 'assistant'
+  content: string
+  createdAt: string
+  confidence?: number
+  sources?: string[]
+  actions?: AssistantAction[]
+}
+
+export interface SuggestedQuestion {
+  id: string
+  question: string
+  category: string
+}