refactor: remove Schattenmarkt from all user-visible UI strings

- Pipeline.tsx: FUTURE_AVAILABILITY label → 'Future Availability'
- ReminderTypeBadge: SCHATTENMARKT_RELEASE label → 'Pre-Market'
- ReminderFilterBar: SCHATTENMARKT_RELEASE label → 'Pre-Market'
- ReminderKpiBar: 'Schattenmarkt-Risiko' → 'Pre-Market Risiko'
- ReminderDetailDrawer: section title + switch label → 'Pre-Market'
- mock-data/matches: explainabilitySummary → 'Pre-Market freigegeben'
- mock-data/reminders: notes → 'Pre-Market Freigabe'

Internal identifiers (schattenmarktRelease field, useSchattenmarktSignals hook,
signal ID prefix schattenmarkt-*) are unchanged — renaming them touches too many
call sites for no user-visible gain.

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

src/pages/demand/Pipeline.tsx

@@ -23,7 +23,7 @@ const RESULT_TYPE_LABEL: Record<PipelineItem['resultType'], string> = {
   VERIFIED_PORTFOLIO: 'Portfolio',
   EXTERNAL_MARKET: 'Direktinserat',
   MAISON_WORK: 'Maison Work',
-  FUTURE_AVAILABILITY: 'Schattenmarkt',
+  FUTURE_AVAILABILITY: 'Future Availability',
 }
 
 const RESULT_TYPE_COLOR: Record<PipelineItem['resultType'], string> = {