db: Appwrite schema (isletmem db, 11 tables, indexes) + SDK helpers

- Created database 'isletmem' with 11 tables via Appwrite MCP:
  tenant_settings, customers, services, software, customer_software,
  calendar_events, tasks, finance_entries, invoices, invoice_items, audit_logs
- All tables use rowSecurity=true; row-level perms scoped to Appwrite Team (tenant)
- 18 indexes (composite on tenantId + queried columns; unique for invoice numbers, tenant_settings)
- src/lib/appwrite/schema.ts as TS source of truth (DATABASE_ID, TABLES, row types)
- src/lib/appwrite/client.ts (browser SDK)
- src/lib/appwrite/server.ts (node-appwrite admin + session clients)
- .env.example template, .env.local for dev (gitignored)
- typecheck script added

.env.example

@@ -0,0 +1,11 @@
+# Appwrite (self-hosted, v1.9.0)
+NEXT_PUBLIC_APPWRITE_ENDPOINT=https://db.kovaksoft.com/v1
+NEXT_PUBLIC_APPWRITE_PROJECT_ID=
+NEXT_PUBLIC_APPWRITE_DATABASE_ID=isletmem
+
+# Server-only — Appwrite API key with sufficient scopes
+# (databases.read/write, tables.read/write, users.read/write, teams.read/write)
+APPWRITE_API_KEY=
+
+# App
+APP_URL=http://localhost:3000