fix(dashboard): keep GitHub device sign-in visible until completion

[AbdullahM07]

Summary

Keep the GitHub device code and verification link visible until that grant completes, then refresh Settings to show the newly connected identity.

Motivation

Settings hid the pending action whenever any GitHub source was connected. The shared provider also discarded it based on an existing App connection or a stale CLI identity. A valid device-code response could therefore disappear immediately, and successful polling did not update Settings' separate status snapshot.

Related issue

Fixes #851

Changes

• Give the pending login panel precedence over connection badges and background status loading.
• Complete device grants through their existing poll endpoint; reserve status-based completion for terminal login.
• Refresh the Settings snapshot when a pending device/token action finishes.
• Exercise the real provider and Settings component in five interaction regressions, using Happy DOM as a test dependency.

Verification

• Before the fix: four of the five regression cases fail, covering stale connectivity, an existing App, pending status refresh, and the final connected identity.
• bun run --cwd apps/dashboard test --maxWorkers=2: 114 files, 1186 tests passed.
• bun run --cwd apps/dashboard lint: passed.
• Root non-CLI workspace tests: all six tasks passed.
• Ran bun run format in an isolated checkout and retained only formatting within this change.
• Rendered the actual click/poll states in Chromium at 1280×800 and 390×844; code, verification link and connected identity remain visible without horizontal overflow. UI detector reported no findings.

Checklist

• One issue per PR, with a scoped diff
• Regression tests fail before the fix and pass afterward
• Relevant tests, typecheck and formatting completed locally
• Reviewed the implementation and test behavior