docs(console): add workspace, providers, and api docs

[vimtor]

Issue for this PR

N/A

Type of change

• Bug fix
• New feature
• Refactor / code improvement
• Documentation

What does this PR do?

Expands the Console docs, replacing the console repo's public/llms.txt (the docs site generates its own llms.txt from the sidebar).

• New Workspace group: Basics, Members, SSO, Directory Sync, Budgets (UI guide), Billing.
• New Providers page after Models: connecting catalog, cloud, and custom providers, choosing and editing models (custom pricing), use in OpenCode.
• API group: new Overview (service accounts, user tokens, device flow, workspace config, errors). BYOK becomes Providers API; Inference and Budgets API move under console/api/.
• Intro gets a get-started section; makes clear a single-member workspace (and Go) needs no team.
• Renames Websearch to Web Search; trims the outdated "For teams" section in Models; clarifies the Go single-member callout.

Behavior was checked against the opencode-console source.

How did you verify your code works?

bun typecheck and bun run build in services/www; loaded each page on the dev server.

Screenshots / recordings

N/A

Checklist

• I have tested my changes locally
• I have not included unrelated changes in this PR