Remove the Hardhat runtime

[clement-ux]

Plain-English summary

The previous layers have replaced both active reasons for keeping Hardhat:

1. Introduce standalone ops CLI #2998 replaces the Hardhat command launcher with pnpm ops;
2. Migrate local forks to Anvil #2999 replaces the Hardhat local/forked node with Anvil.

This PR removes the now-unused Hardhat packages, configuration, wrappers, and compatibility code. It is intentionally the last step: replacement behavior is introduced and tested before the old runtime is deleted.

Before and after

Before this stack:
  ops commands → Hardhat
  local forks  → Hardhat node

After this PR:
  ops commands → standalone TypeScript CLI
  local forks  → Anvil
  contracts    → Foundry (unchanged by this stack)

What changes in this PR

• remove Hardhat packages, configuration, node wrapper, and runtime helpers;
• replace the temporary registration shim with a small local task / subtask registry;
• remove fallback Hardhat RPC namespaces; Anvil is now the only local-node API;
• rename signer and descriptor tooling to runtime-neutral names;
• update active documentation, runlogs, fixtures, skills, and comments;
• remove the stale Slither finding for the deleted dependency console.

What must remain true

• all 75 public ops commands remain in the catalogue;
• all 74 registry-backed commands have live handlers; accounts remains a direct standalone command;
• mainnet forks remain distinguishable from live mainnet through FORK=true;
• the active runtime has no Hardhat dependency;
• no tracked content or filename contains hardhat.

Stack and merge order

Base: #2999 (chore/migrate-local-node-to-anvil)

1. Remove obsolete historical scripts and artifacts #2997 — remove obsolete historical scripts and artifacts
2. Introduce standalone ops CLI #2998 — introduce standalone ops CLI
3. Migrate local forks to Anvil #2999 — migrate local forks to Anvil
4. Remove the Hardhat runtime #3000 — remove the Hardhat runtime (this PR)

Merge in cascade: #3000 → #2999 → #2998 → #2997 → master. Do not merge this PR directly into master.

What to review

Please focus on completeness rather than replacement behavior, which is introduced in the parent layers:

• is every active Hardhat entry point now replaced before being removed?
• are any package, config, helper, filename, or documentation references left behind?
• do command registration, signer handling, and network detection still preserve the stated invariants?

Validation

• pnpm install --frozen-lockfile
• pnpm test:tasks — 39 passing
• pnpm test:anvil — 3 passing
• pnpm test:brownie — 4 passing
• pnpm test:scripts — 66 passing
• pnpm test:layouts — 11 passing
• pnpm typecheck
• pnpm lint:js, pnpm lint:ts, pnpm prettier:check
• forge build contracts/ -j 1
• full GitHub CI passes
• verified that the full stack produces exactly the same final tree as the previous Remove stale Hardhat tooling and scripts #2993–Remove Hardhat completely #2995 stack on current master