ci: Add Foundry tooling integration test (#511)

## Description

Adds a CI workflow that builds and tests a small Foundry project with
`foundry-polkadot`'s `forge`, exercising the standard JSON interface
between `resolc` and `foundry-polkadot` end-to-end.

## Resolved Issues

Closes #513

tooling-projects/foundry/erc20/verify-compiler-output.sh

@@ -0,0 +1,33 @@
+#!/usr/bin/env bash
+
+# Asserts that the compiled project contains the expected compiler output.
+# Requires `forge` in PATH. Run from the project's root.
+#
+# Usage: verify-compiler-output.sh <resolc-path>
+
+set -euxo pipefail
+
+if [[ $# -ne 1 ]]; then
+    echo "usage: $(basename "$0") <resolc-path>" >&2
+    exit 2
+fi
+
+resolc=$1
+
+inspect() {
+    forge inspect --use-resolc "$resolc" MyToken "$@"
+}
+
+inspect bytecode          | grep '^0x50564d'                      > /dev/null
+inspect deployedBytecode  | grep '^0x50564d'                      > /dev/null
+inspect irOptimized       | grep .                                > /dev/null
+inspect ir                | grep .                                > /dev/null
+inspect assembly          | grep .                                > /dev/null
+inspect abi               --json | jq -e 'length > 0'             > /dev/null
+inspect methodIdentifiers --json | jq -e 'length > 0'             > /dev/null
+inspect storageLayout     --json | jq -e '.storage | length > 0'  > /dev/null
+inspect metadata          --json | jq -e 'length > 0'             > /dev/null
+inspect devdoc            --json | jq -e 'length > 0'             > /dev/null
+inspect userdoc           --json | jq -e 'length > 0'             > /dev/null
+
+echo "all checks passed"