feat: migrate deployment to Hardhat Ignition

Replace the imperative deploy scripts with Hardhat Ignition modules:
- ignition/modules/{MockToken,Reputation,P2PIX}.ts orchestrate the full
  deployment graph; P2PIX.ts wires MockToken + Reputation and deploys
  P2PIX via its constructor
- ignition/parameters/localhost.json holds per-network values
  (defaultBlocks, validSigners, MockToken supply)
- swap hardhat-toolbox for the individual plugins that Ignition needs;
  add hardhat-verify (v2) and bump hardhat/hardhat-tracer accordingly
- delete scripts/1-deploy-mockToken.ts and scripts/2-deploy-p2pix.ts
- add deploy:{localhost,goerli,sepolia,mumbai} npm scripts
- include ignition/**/* in tsconfig.json
- gitignore ignition/deployments/chain-31337/ (ephemeral local state)

This branch carries the deployment-tooling migration only — the contract
is still the original constructor-based P2PIX. Proxy / UUPS deploy
support will land alongside the upgradeable contract change.

ignition/modules/P2PIX.ts

@@ -0,0 +1,32 @@
+import { buildModule } from "@nomicfoundation/hardhat-ignition/modules";
+
+import MockTokenModule from "./MockToken";
+import ReputationModule from "./Reputation";
+
+export default buildModule("P2PIX", m => {
+  const { token } = m.useModule(MockTokenModule);
+  const { reputation, multicall } = m.useModule(
+    ReputationModule,
+  );
+
+  const defaultBlocks = m.getParameter("defaultBlocks", 10);
+  const validSigners = m.getParameter<string[]>(
+    "validSigners",
+    [],
+  );
+
+  const p2pix = m.contract("P2PIX", [
+    defaultBlocks,
+    validSigners,
+    reputation,
+    [token],
+    [true],
+  ]);
+
+  return {
+    p2pix,
+    reputation,
+    multicall,
+    token,
+  };
+});