test: port periphery suite (routers + examples) to Hardhat

V1-free v2Fixture (no migrator / flash-swap); full suite is 145 passing.

- port ListaV2Router01/02 and 4 example specs to ethers v5 + hardhat-waffle
- Router01: single module-level fixture-loader with hooks scoped inside the
  per-version describe (the shared Hardhat chain corrupts EVM snapshots when
  the loop registers hooks + a second loader at the outer describe scope)
- oracle specs: add allowBlocksWithSameTimestamp + initialDate (2019) and an
  anchor-mining mineBlock to reproduce the ganache clock model they assume
- swapExactETHForTokens gas snapshot 138770 -> 138700 (fork bytecode)

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

Author: razww

README.md

@@ -37,8 +37,16 @@ contracts/
   periphery/   # forked from Uniswap/v2-periphery (solc 0.6.6)
 test/
   core/        # ported Uniswap V2 core specs (Hardhat + ethers v5 + waffle matchers)
+  periphery/   # ported router + example specs (V1-free fixture, no migrator/flash-swap)
 ```
 
+The full suite (core + periphery) is **145 tests**. The Uniswap V1 migrator and
+V1↔V2 flash-swap specs are intentionally absent, matching the removed contracts.
+A few gas-snapshot constants were adjusted to this fork's bytecode, and the
+timestamp-sensitive oracle specs rely on `allowBlocksWithSameTimestamp` +
+`initialDate` (set in `hardhat.config.ts`) to reproduce the ganache clock model
+they were written against.
+
 Periphery imports that originally referenced the `@uniswap/v2-core` npm package
 have been rewired to the local `contracts/core` fork. `@uniswap/lib` imports are
 resolved from `node_modules` as before.

hardhat.config.ts

@@ -26,6 +26,13 @@ const config: HardhatUserConfig = {
       chainId: 1,
       hardfork: "istanbul",
       allowUnlimitedContractSize: true,
+      // Start the chain before 2020 so the sliding-window oracle spec can set
+      // its absolute start timestamp (1577836800 = 2020-01-01) going forward.
+      initialDate: "2019-01-01T00:00:00Z",
+      // The Uniswap oracle specs were written against ganache, where consecutive
+      // txs in the same real second share a block timestamp. Allow that here so
+      // setup txs don't drift past the anchored start time.
+      allowBlocksWithSameTimestamp: true,
     },
   },
   paths: {