feat(#240): Mission Control Strip frontend — 5 components + dashboard wiring

Adds the full-width 3-column collaboration widget below the existing
dashboard grid. Renders without the backend running (Promise.allSettled
isolation keeps failures silent).

Components (src/lib/components/):
- ExpertBadge.svelte — purple pill with icon, no props
- SegmentationColumn.svelte — col 1: links to /enrich/{id}, weekly pulse
- TranscriptionColumn.svelte — col 2: per-doc progress bar when blocks exist
- ReadyColumn.svelte — col 3: mint border when filled, dashed empty state
- MissionControlStrip.svelte — strip wrapper, 1-col mobile / 3-col sm+

i18n: 19 new keys added to de/en/es (mission_control_*)

Page wiring:
- +page.server.ts: 4 new Promise.allSettled calls for segmentation-queue,
  transcription-queue, ready-to-read, weekly-stats; all failures silent
- +page.svelte: MissionControlStrip rendered below the grid in isDashboard

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

frontend/messages/de.json

@@ -555,5 +555,22 @@
 	"training_seg_too_few_blocks": "Mindestens 5 Segmentierungsblöcke erforderlich (aktuell: {available}).",
 	"transcription_block_segmentation_only": "Nur Segmentierung",
 	"training_chip_kurrent": "Kurrent-Erkennung",
-	"training_chip_segmentation": "Segmentierung"
+	"training_chip_segmentation": "Segmentierung",
+	"mission_control_heading": "Mitarbeiten",
+	"mission_control_segmentation_heading": "Segmentierung",
+	"mission_control_segmentation_description": "Textbereiche markieren — keine Vorkenntnisse nötig",
+	"mission_control_segmentation_cta": "Segmentieren",
+	"mission_control_segmentation_empty": "Alle Dokumente haben bereits Segmentierungsblöcke.",
+	"mission_control_transcription_heading": "Transkription",
+	"mission_control_transcription_description": "Text abschreiben — Kurrent-Kenntnisse hilfreich",
+	"mission_control_transcription_cta": "Transkribieren",
+	"mission_control_transcription_empty": "Keine Dokumente warten auf Transkription.",
+	"mission_control_ready_heading": "Lesefertig",
+	"mission_control_ready_description": "Vollständig transkribiert und geprüft",
+	"mission_control_ready_empty": "Noch keine Dokumente vollständig transkribiert.",
+	"mission_control_ready_empty_cta": "Jetzt mitmachen",
+	"mission_control_weekly_pulse": "↑ +{count} diese Woche",
+	"mission_control_expert_badge": "Experten gesucht",
+	"mission_control_blocks_progress": "{texted} / {total} Blöcke",
+	"mission_control_reviewed_pct": "{pct}% geprüft"
 }