feat(connections): extract shared OAuth flow and auto-authenticate from empty state

[viktormarinho]

Summary

• Extract the full OAuth flow (popup → token save → query invalidation) from connection/index.tsx into authenticate-connection.ts — a shared helper usable by any component
• connection/index.tsx: handleAuthenticate delegates to the helper (no behavior change)
• no-llm-binding-empty-state.tsx: "Connect OpenRouter" now triggers OAuth immediately in a popup, staying on the Home page, instead of navigating away to the connection detail page

Test plan

• Authenticate an existing connection from the connection detail page — still works
• Click "Connect OpenRouter" from the empty chat state — OAuth popup opens, on success shows toast and model selector becomes available without navigating away
• If an OpenRouter connection already exists but is unauthenticated, clicking the button re-triggers auth (doesn't create a duplicate)
• Auth failure shows an error toast

Split from #2528

🤖 Generated with Claude Code

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Summary by cubic

Extracted the OAuth flow into a shared helper and enabled one-click OpenRouter authentication from the empty chat state without leaving Home. This reduces duplication and refreshes UI state automatically after auth.

• New Features

  • “Connect OpenRouter” now opens an OAuth popup in place; on success shows a toast and unlocks the model selector.
  • Reuses an existing OpenRouter connection when present; no duplicates.
  • Errors surface via toast.

• Refactors

  • Moved full OAuth flow (popup → token save → query invalidation) to apps/mesh/src/web/lib/authenticate-connection.ts.
  • Connection detail view now delegates to the helper with no behavior change.

^{Written for commit 727aa37. Summary will update on new commits.}

[github-actions]

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[github-actions]

Release Options

Should a new version be published when this PR is merged?

React with an emoji to vote on the release type:

Reaction	Type	Next Version
👍	Prerelease	2.123.5-alpha.1
🎉	Patch	2.123.5
❤️	Minor	2.124.0
🚀	Major	3.0.0

Current version: 2.123.4

Deployment

• Deploy to production (triggers ArgoCD sync after Docker image is published)

[cubic-dev-ai]

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