frontend: patient delete + complete sheet + Obsidian-style record graph

- deletePatient() lib fn (DELETE /api/patients/:fileNumber already existed)
- confirmed delete button in the patient sheet (full-clinician only)
- aggregate appointments/prescriptions/invoices into the sheet (by file #)
- new shared RecordGraph (@xyflow/react + d3-force) linking problems↔visits,
  added as a "Record graph" section + reusable by AI Graph mode
- i18n keys for delete + new sheet sections

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

frontend/package.json

@@ -23,6 +23,7 @@
     "@tiptap/pm": "^3.25.0",
     "@tiptap/react": "^3.25.0",
     "@tiptap/starter-kit": "^3.25.0",
+    "@types/d3-force": "^3.0.10",
     "@visx/curve": "^4.0.1-alpha.0",
     "@visx/event": "^4.0.1-alpha.0",
     "@visx/gradient": "^4.0.1-alpha.0",
@@ -39,6 +40,7 @@
     "clsx": "^2.1.1",
     "cmdk": "^1.1.1",
     "d3-array": "^3.2.4",
+    "d3-force": "^3.0.0",
     "embla-carousel-react": "^8.6.0",
     "framer-motion": "^12.40.0",
     "i18next": "^26.3.1",