fix: address review feedback on LocalSwapWidget and CheatsView

- LocalSwapWidget: move useWallet() to top-level <script setup> (was
  incorrectly called inside async buyKrk() event handler)
- LocalSwapWidget + CheatsView: fix misleading toast — all transactions
  are fully confirmed at that point, so say 'Swap complete' not 'Swap
  submitted'
- LocalSwapWidget: add $KRK sigil to warning/hint text for consistency
  with GetKrkView
- LocalSwapWidget: add comment on amountOutMinimum: 0n explaining it is
  intentional for a no-MEV local anvil environment
- CheatsView: apply same useWallet() fix (pre-existing anti-pattern)
- docs/ENVIRONMENT.md: document VITE_ENABLE_LOCAL_SWAP and related
  VITE_ variables in a new webapp env-var table

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

docs/ENVIRONMENT.md

@@ -81,6 +81,15 @@ docker inspect landing --format '{{.NetworkSettings.Networks.harb_harb-network.I
 For testing login: `lobsterDao`, `test123`, `lobster-x010syqe?412!`
 (defined in `web-app/src/views/LoginView.vue`)
 
+## Webapp Environment Variables
+
+| Variable | Default | Set in docker-compose | Purpose |
+|---|---|---|---|
+| `VITE_ENABLE_LOCAL_SWAP` | `false` (unset) | `true` | Show inline ETH→$KRK swap widget on Get KRK page instead of the Uniswap link. Enable for local dev; leave unset for production builds. |
+| `VITE_KRAIKEN_ADDRESS` | from `deployments-local.json` | via `contracts.env` | Override KRK token address. |
+| `VITE_STAKE_ADDRESS` | from `deployments-local.json` | via `contracts.env` | Override Stake contract address. |
+| `VITE_DEFAULT_CHAIN_ID` | auto-detected (31337 on localhost) | — | Force the default chain. |
+
 ## Contract Addresses
 
 After bootstrap, addresses are in `/home/debian/harb/tmp/containers/contracts.env`.