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/domain/marktHinweis.ts

@@ -0,0 +1,27 @@
+import type { AssetType } from './enums'
+
+export type HinweisVisibility = 'INTERN' | 'PLATTFORM'
+export type HinweisDirection = 'SUCHE' | 'VERFUEGBARKEIT'
+export type HinweisStatus = 'OFFEN' | 'IN_BEARBEITUNG' | 'ARCHIVIERT'
+export type HinweisQuelle = 'NETZWERKEVENT' | 'TELEFONAT' | 'BESICHTIGUNG' | 'MESSE' | 'EMAIL' | 'SONSTIGES'
+
+export interface MarktHinweis {
+  id: string
+  createdAt: string
+  createdBy: string
+  verwaltungId: string
+  verwaltungName: string
+  direction: HinweisDirection
+  assetType: AssetType
+  locationHint: string
+  areaSqmMin?: number
+  areaSqmMax?: number
+  companyName?: string
+  isAnonymized: boolean
+  quelle: HinweisQuelle
+  note?: string
+  visibility: HinweisVisibility
+  status: HinweisStatus
+}
+
+export type CreateMarktHinweisInput = Omit<MarktHinweis, 'id' | 'createdAt' | 'createdBy' | 'verwaltungId' | 'verwaltungName'>