Add per-event finance, event team permissions and public door sales state.

Event finance
- Finance tab on the event page: P&L summary with a revenue-to-result
  waterfall, costs and other income in one ledger, and the partner split
  with payouts. Lifecycle stepper (Selling, Adding costs, Ready to close,
  Finalized) with what is left to do; closing the books goes through a
  checklist dialog that freezes the numbers.
- Expense modal shows only the fields each calculation type needs, a live
  preview with the event's real counts, and a category suggested from the
  description. Date inputs follow the UI language.
- Global Finance page: profit per event with outliers clipped and labelled,
  and a "Ready to close" list of past events whose books are still open.
- Calculation service (integer PYG, basis points) with pinned regression
  scenarios; PYG formatting centralised in lib/money with locale-aware
  separators.

Event team permissions
- Per-event members with role presets and requireEventPermission; the
  header stat "Confirmed" is relabelled "Not checked in yet", which is
  what it counts.

Public sales state
- One sales state (online, door, sold out, ended, external, cancelled) for
  the event page, listings and JSON-LD, with the door price and tenders
  shown only while people can still pay at the door.

Frontend unit tests run with vitest (npm test in frontend/).

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

frontend/package.json

@@ -6,7 +6,8 @@
     "dev": "dotenv -e .env -- next dev",
     "build": "next build",
     "start": "dotenv -e .env -- next start",
-    "lint": "next lint"
+    "lint": "next lint",
+    "test": "vitest run"
   },
   "dependencies": {
     "@heroicons/react": "^2.1.4",
@@ -23,6 +24,7 @@
     "react-dom": "^18.3.1",
     "react-hot-toast": "^2.4.1",
     "react-markdown": "^10.1.0",
+    "recharts": "^2.15.4",
     "remark-gfm": "^4.0.1"
   },
   "devDependencies": {
@@ -33,6 +35,7 @@
     "dotenv-cli": "^11.0.0",
     "postcss": "^8.4.38",
     "tailwindcss": "^3.4.4",
-    "typescript": "^5.5.2"
+    "typescript": "^5.5.2",
+    "vitest": "^4.1.10"
   }
 }