CI: [V2:23] Roll Out Local Build Workspace

[ritorhymes]

Part of V2: Multi-repo local build system.
Stacked on #11

Summary

This PR is the ERCs repo rollout for the V2 local build workspace. It wires ERCs into the contributor workflow without changing proposal content: contributors can run a repo-local setup script, get the expected surrounding workspace, and use the updated build-eips command surface for checking, building, serving, previewing, and publishing ERCs.

• Add POSIX and PowerShell scripts/dev-setup entrypoints for ERCs contributors.
• Locate, reuse, or install build-eips and Zola. build-eips release archives are verified against fetched .sha256 sidecars; Zola archives are verified against per-platform hashes pinned in the scripts.
• Bootstrap the surrounding workspace one directory above this repo, with this repo as <workspace>/ERCs/.
• Run build-eips init with --template --platform-dev so the contributor workspace includes proposal siblings, theme, template, preprocessor, and eipw checkouts.
• Run build-eips doctor after init and surface doctor failures as warnings rather than hard setup failures.
• Update CI from check --format github to editorial check --against-upstream --format github.
• Update publish builds from build --no-lint and its accompanying justification comment to plain build.
• Add a .github/CONTRIBUTING.md pointer to ./scripts/dev-setup and the generated WORKSPACE.md command/configuration reference.
• Expand README.md with local workflow documentation for setup, check/build/serve/preview, local settings, targeted rendering, editorial validation, and workspace reference handoff.
• Move ERCs homepage badges into structured front matter, including the ERCRef Discord badge.

Closes eips-wg/theme/issues/5
Closes eips-wg/preprocessor/issues/14

Review Notes

This is the ERCs repo rollout for the V2 multi-repo local build system. It wires this repository into the workspace model introduced by the preprocessor stack; it does not change proposal content.

The setup scripts are repo-local convenience wrappers for ERCs contributors. They install a released build-eips binary when needed, or reuse an existing build-eips on PATH or in the default user-local install path. They do not build build-eips from this repo.

Unlike the theme setup script in V2:19, the ERCs setup script treats this repo as the active proposal root, hard-codes --template --platform-dev, and does not accept CLI flags or an ACTIVE_REPO_ROOT override. ERCs contributors always get the full contributor workspace.

Zola follows the same reuse-first shape: the scripts use Zola from PATH or the default user-local install path when available. They install Zola 0.22.1 if the discovered version is missing, older than 0.22.1, or unparseable; they reuse 0.22.1 and warn-but-continue for newer versions.

build-eips release downloads are verified against fetched .sha256 sidecars. That depends on the release-side checksum generation added in V2:17. Zola downloads are verified against per-platform hashes pinned in these scripts.

The setup scripts always pass --template --platform-dev to build-eips init. The behavior of those init flags lives in the preprocessor setup path; --platform-dev was added in V2:17.

The CI command moves to editorial check --against-upstream --format github, which is the targeted editorial validation surface introduced in V2:14.

Publish previously passed --no-lint to skip eipw linting on the master checkout. After V2:15 moved eipw out of build/check/serve entirely, that flag is no longer needed and publish can use plain build.

Much of the README diff rewrites existing prose into a new local-workflow structure and unwraps paragraphs; those parts are documentation reshaping, not proposal-content or command-behavior changes.

The README intentionally documents the final preprocessor command surface for ERCs contributors, then points to generated ../WORKSPACE.md for the full command reference from V2:18.

[throwaway-for-circle-ci-bot]

File .github/CONTRIBUTING.md

Requires 2 more reviewers from @g11tech, @jochem-brouwer, @lightclient, @SamWilsn, @xinbenlv

File .github/actions/build-eips/action.yml

Requires 2 more reviewers from @g11tech, @jochem-brouwer, @lightclient, @SamWilsn, @xinbenlv

File .github/workflows/ci.yml

Requires 2 more reviewers from @g11tech, @jochem-brouwer, @lightclient, @SamWilsn, @xinbenlv

File .github/workflows/publish.yml

Requires 2 more reviewers from @g11tech, @jochem-brouwer, @lightclient, @SamWilsn, @xinbenlv

File Build.toml

Requires 2 more reviewers from @g11tech, @jochem-brouwer, @lightclient, @SamWilsn, @xinbenlv

File README.md

Requires 2 more reviewers from @g11tech, @jochem-brouwer, @lightclient, @SamWilsn, @xinbenlv

File content/_index.md

Requires 2 more reviewers from @g11tech, @jochem-brouwer, @lightclient, @SamWilsn, @xinbenlv

File scripts

Requires 2 more reviewers from @g11tech, @jochem-brouwer, @lightclient, @SamWilsn, @xinbenlv

File scripts/dev-setup

Requires 2 more reviewers from @g11tech, @jochem-brouwer, @lightclient, @SamWilsn, @xinbenlv

File scripts/dev-setup.ps1

Requires 2 more reviewers from @g11tech, @jochem-brouwer, @lightclient, @SamWilsn, @xinbenlv