Replace the hardhat test harness with plain ethers and mocha

[rickstaa]

This repo compiles no contracts. hardhat is used only as an RPC provider, a source of signers, and a mocha launcher for test/test.ts, against the geth container in docker-compose.test.yml.

hardhat 2 is end of life, and @nomiclabs/hardhat-ethers, @nomiclabs/hardhat-waffle and ethereum-waffle are unmaintained. They pull in request, solc, an old pinned mocha, and most of the packages behind the remaining Dependabot alerts. Migrating to hardhat 3 means an ESM config, ethers v6 and a test rewrite anyway, for features this repo does not use.

Proposal: drop hardhat and waffle entirely.

• ethers.JsonRpcProvider for the connection, listAccounts for the geth dev signers, provider.send("evm_mine") for block mining.
• mocha run directly with ts-node, or node:test.
• The two .to.emit assertions become a receipt-log helper or a standalone chai matcher.
• apollo-fetch replaced by native fetch.
• typechain target moves to ethers-v6.
• Fix the ticket test while rewriting it, see Ticket redemption test fails against the streamflow geth image #267.

This deletes hardhat, waffle, solc and their dependency trees, and with them most of the temporary resolutions in package.json. A plain-ethers harness also works unchanged against the anvil-based test image planned in the testnet proposal.

Rough size: the 823-line test file, hardhat.config.ts, package.json.

[rickstaa]

Sizing from an inventory of test/test.ts: hardhat is used only for ethers (provider and signers) and the SignerWithAddress type; waffle only for two .to.emit assertions; provider calls are getBlock, getBlockNumber, on and evm_mine; apollo-fetch has one call site; mocha config is a single timeout in hardhat.config.ts.

Steps, staying on ethers v5 so typechain and the existing ethers.utils / BigNumber idioms are untouched:

1. new ethers.providers.JsonRpcProvider(url) with the URL from the env, listAccounts + getSigner in place of getSigners.
2. A small expectEvent(receipt, contract, name) helper parsing receipt logs with the contract interface, replacing the two .to.emit uses.
3. Native fetch replacing createApolloFetch.
4. mocha -r ts-node/register in the test scripts with the timeout; delete hardhat.config.ts.
5. Remove hardhat, @nomiclabs/hardhat-ethers, @nomiclabs/hardhat-waffle, ethereum-waffle and apollo-fetch from package.json, then prune the matching rows in Remove the temporary yarn resolutions as their parents are upgraded #269.
6. Fix or skip the ticket test from Ticket redemption test fails against the streamflow geth image #267 in the same rewrite.

Roughly half a day including a docker suite run. ethers v6 is a separate follow-up (retarget typechain, rewrite the v5 idioms), not needed for the alert cleanup.