Fix stale homepage badge links with structured badge metadata

[ritorhymes]

Problem

The EIPs/ERCs homepages currently render their Discord and RSS badges as inline markdown image links. Some of those badge links are stale, which results in dead homepage links.

Because the badge URLs are embedded directly in page body markdown, fixing and maintaining the badge set requires editing rendered content instead of treating the badges as homepage metadata. The same badge set also needs to stay consistent across both EIPs and ERCs.

Solution

Move homepage badges into structured page front matter under extra.homepage_badges, and let the theme render that data.

The badge data lives in each repo’s content/_index.md:

extra:
  homepage_badges:
    - href: https://discord.gg/Nz6rtfJ8Cu
      image: https://dcbadge.limes.pink/api/server/Nz6rtfJ8Cu?style=flat
      alt: Badge for EIP Editor Discord channel

The theme reads section.extra.homepage_badges and renders the badges on the homepage. This replaces the inline markdown badge links and centralizes badge rendering in the theme.

Scope

Theme:

• Render homepage badges from section.extra.homepage_badges.
• Render image badges when image is present.
• Render text badges when only label is present.
• Keep badge layout/styling in the theme.

EIPs:

• Move homepage Discord/RSS badges from inline markdown into extra.homepage_badges.
• Include the ERCRef Discord badge in the structured badge list.

ERCs:

• Move homepage Discord/RSS badges from inline markdown into extra.homepage_badges.
• Include the ERCRef Discord badge in the structured badge list.

Implementation

This is folded into the multi-repo local build rollout.

Relevant PRs:

• Theme renderer: [V2:19] Add Theme Development Setup theme#12
• EIPs rollout: CI: [V2:20] Add Repo Manifest EIPs#11
• ERCs rollout: CI: [V2:21] Add Repo Manifest for ERCs ERCs#11

The larger rollout is tracked in #15.