feat: Marktchancen — Netzwerk-Hinweise tab (human-sourced market intel)

- MarktHinweis domain type: SUCHE/VERFUEGBARKEIT direction, INTERN/PLATTFORM
  visibility, anonymization flag, source tracking
- Full data layer: IMarktHinweisProvider, MockupMarktHinweisProvider, service, hooks
- 7 seed entries: mix of intern/shared, demand/supply, own/partner Verwaltungen
- Marktchancen gets two-tab layout: Digitale Signale (crawler) + Netzwerk (human)
- HinweisListItem: direction icon, visibility badge (Intern/Geteilt/partner name)
- HinweisDetail: note card, portfolio match (SUCHE) or availability info (VERFUEGBARKEIT)
- HinweisErfassenDialog: direction toggle, asset type, location, area range,
  company + anonymize switch, source, note, card-based visibility picker
- HinweisPropertyCard: same Anschreiben composer pattern as crawler side

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

src/provider/IMarktHinweisProvider.ts

@@ -0,0 +1,8 @@
+import type { MarktHinweis, CreateMarktHinweisInput } from '../domain/marktHinweis'
+
+export interface IMarktHinweisProvider {
+  getAll(): Promise<MarktHinweis[]>
+  getById(id: string): Promise<MarktHinweis | null>
+  create(data: CreateMarktHinweisInput): Promise<MarktHinweis>
+  update(id: string, data: Partial<MarktHinweis>): Promise<MarktHinweis>
+}

src/provider/MockupMarktHinweisProvider.ts

@@ -0,0 +1,36 @@
+import type { IMarktHinweisProvider } from './IMarktHinweisProvider'
+import type { MarktHinweis, CreateMarktHinweisInput } from '../domain/marktHinweis'
+import { marktHinweise as seed } from '../mock-data/marktHinweise'
+
+const store: MarktHinweis[] = [...seed]
+
+export const MockupMarktHinweisProvider: IMarktHinweisProvider = {
+  async getAll() {
+    return [...store]
+  },
+
+  async getById(id: string) {
+    return store.find(h => h.id === id) ?? null
+  },
+
+  async create(data: CreateMarktHinweisInput) {
+    const next: MarktHinweis = {
+      ...data,
+      id: `mh-${Date.now()}`,
+      createdAt: new Date().toISOString(),
+      createdBy: 'Thomas Müller',
+      verwaltungId: 'v-001',
+      verwaltungName: 'Wincasa AG',
+    }
+    store.push(next)
+    return next
+  },
+
+  async update(id: string, data: Partial<MarktHinweis>) {
+    const idx = store.findIndex(h => h.id === id)
+    if (idx === -1) throw new Error(`MarktHinweis ${id} not found`)
+    const updated: MarktHinweis = { ...store[idx], ...data }
+    store[idx] = updated
+    return updated
+  },
+}