docs: expose the ecosystem-wide contributor queue

[EmersonBraun]

What changed

• adds an organization-wide good-first-issue queue to the existing contribution page
• highlights the three current bounded entry tasks in Chat, Doc Bridge, and Code Review CLI
• replaces the repository-local fallback with the organization-wide search

Why

The current live component queries only AgentsKit-io/agentskit, so contributor traffic cannot see the entry tasks created across the ecosystem.

Validation

• pnpm --filter @agentskit/core build
• pnpm --filter @agentskit/react build
• pnpm --filter @agentskit/docs-next build
• pnpm docs:bridge:gate

Only apps/docs-next/content/docs/reference/contribute/good-first-issues.mdx changed.

[github-actions]

Lighthouse

URL	Performance	Accessibility	Best practices	SEO
http://127.0.0.1:3000/	41	92	96	100
http://127.0.0.1:3000/docs	71	100	96	100
http://127.0.0.1:3000/docs/get-started/getting-started/quickstart	70	96	96	100
http://127.0.0.1:3000/stack	93	100	96	100
http://127.0.0.1:3000/showcase	88	100	96	100

Run by .github/workflows/lighthouse.yml.

[github-actions]

Lighthouse

URL	Performance	Accessibility	Best practices	SEO
http://127.0.0.1:3000/	40	92	96	100
http://127.0.0.1:3000/docs	66	100	96	100
http://127.0.0.1:3000/docs/get-started/getting-started/quickstart	71	96	96	100
http://127.0.0.1:3000/stack	89	100	96	100
http://127.0.0.1:3000/showcase	92	100	96	100

Run by .github/workflows/lighthouse.yml.