chore: initial trade-visualizer import

.env.example

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+# Default: UI reads ticks from the same-origin API proxy at `/api`.
+VITE_API_URL=/api
+
+# Hasura GraphQL endpoint (supports subscriptions via WS).
+# On VPS, `trade-frontend` proxies Hasura at the same origin under `/graphql`.
+VITE_HASURA_URL=/graphql
+# Optional explicit WS URL; when omitted the app derives it from `VITE_HASURA_URL`.
+# Can be absolute (wss://...) or a same-origin path (e.g. /graphql-ws).
+# VITE_HASURA_WS_URL=/graphql-ws
+# Optional auth (only if Hasura is not configured with `HASURA_GRAPHQL_UNAUTHORIZED_ROLE=public`):
+# VITE_HASURA_AUTH_TOKEN=YOUR_JWT
+VITE_SYMBOL=SOL-PERP
+# Optional: filter by source (leave empty for all)
+# VITE_SOURCE=drift_oracle
+VITE_POLL_MS=1000
+VITE_LIMIT=300