Add OAuth device code flow

[ejsmith]

Summary

Adds RFC 8628-style OAuth device authorization for remote and headless MCP/OAuth clients. Device clients can request a device/user code, users can approve access through the Svelte verification page, and token polling now returns the expected pending, slow_down, denied, expired, or token responses.

Changes

• Added urn:ietf:params:oauth:grant-type:device_code support, authorization server metadata, device authorization, consent, approve, deny, and token exchange endpoints.
• Stores pending device authorizations in cache with opaque device codes, normalized user-code lookup, expiration, polling interval enforcement, and one-time consumption.
• Added persisted OAuth application grant_types across models, dynamic registration, repository mapping, admin API, and admin UI.
• Added Svelte /next/oauth/device verification flow with manual code entry and verification_uri_complete support.
• Updated OAuth HTTP samples, AI tools copy, controller tests, admin tests, and OpenAPI baseline.

Compatibility

Existing authorization-code clients continue to default to authorization_code refresh_token. Authorization-code clients still require redirect URIs; device-only clients may omit redirects.

Validation

• dotnet test --project tests/Exceptionless.Tests/Exceptionless.Tests.csproj -- --filter-class Exceptionless.Tests.Controllers.OAuthControllerTests
• dotnet test --project tests/Exceptionless.Tests/Exceptionless.Tests.csproj -- --filter-class Exceptionless.Tests.Controllers.OAuthApplicationControllerTests
• dotnet build --no-restore -v:q
• cd src/Exceptionless.Web/ClientApp; npm run build
• OpenAPI baseline snapshot regenerated and verified
• git diff --check

[ejsmith]

/preview

[github-actions]

Preview deployed

• App: https://dev-app.exceptionless.io
• Collector: https://dev-collector.exceptionless.io
• Commit: e14b150346f2
• Version: 8.6.3-preview.feature.oauth-device-flow.0.5
• Workflow run: view logs

[github-actions]

Package	Line Rate	Branch Rate	Complexity	Health
Exceptionless.AppHost	39%	40%	132	❌
Exceptionless.Core	72%	64%	8824	➖
Exceptionless.Insulation	24%	23%	205	❌
Exceptionless.Web	79%	67%	5258	✔
Summary	73% (17492 / 24094)	64% (8898 / 13868)	14419	➖