fix(auth): correctly handle non-fragment callbacks

[SF2311]

According to https://datatracker.ietf.org/doc/html/rfc6749#section-3.1.2 OIDC callback URLs must not contain a fragment component. Thus, some OIDC providers (at least mine) don't support this, but setting the callback to a path results in 404 from the web server because no actual page exists there.

This PR adds two pages /auth and /silent-auth to allow error-free handling of the callback.
It should thereby resolve #398.

[CLAassistant]

All committers have signed the CLA.

[Copilot]

Pull Request Overview

This PR fixes OIDC authentication callback handling to comply with RFC 6749, which prohibits fragment components in OAuth 2.0 redirect URIs. The changes replace fragment-based callbacks (/#callback, /#silent-callback) with path-based routes (/auth, /silent-auth) to support OIDC providers that enforce this standard.

Key Changes:

• Updated redirect URIs from fragment-based to path-based endpoints
• Added new Next.js page routes to handle authentication callbacks
• Enhanced callback success handler to manage redirects for the new /auth route

Reviewed Changes

Copilot reviewed 5 out of 5 changed files in this pull request and generated 3 comments.

Show a summary per file

File	Description
src/utils/config.ts	Changed default redirect URIs from fragment-based to path-based
src/auth/OIDCProvider.tsx	Added redirect logic for /auth route with query parameter preservation
src/auth/CallbackPage.tsx	New component providing fallback for OIDC callback routes
src/app/auth/page.tsx	New page route for standard authentication callback
src/app/silent-auth/page.tsx	New page route for silent authentication callback

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[Copilot]

Empty catch block silently swallows errors. Consider logging the error or adding a comment explaining why it's safe to ignore.

Suggested change

	} catch (e) { }
	} catch (e) {
	if (process.env.NODE_ENV !== "production") {
	console.error("Error accessing localStorage in CallBackSuccess:", e);
	}
	}

[Copilot]

Magic number 100ms delay lacks explanation. Add a comment or constant explaining why this delay is necessary for token storage.

[Copilot]

Magic number 100ms delay lacks explanation. Add a comment or constant explaining the purpose of this delay.

Suggested change

	export default function CallbackPage() {
	const router = useRouter();
	useEffect(() => {
	// Fallback: if this component renders directly, redirect to /peers
	const timer = setTimeout(() => {
	router.replace("/peers");
	}, 100);
	// Delay before redirecting to allow any pending UI updates or transitions to complete.
	const REDIRECT_DELAY_MS = 100;
	export default function CallbackPage() {
	const router = useRouter();
	useEffect(() => {
	// Fallback: if this component renders directly, redirect to /peers
	// The 100ms delay ensures the UI has time to render before navigation,
	// which can help avoid race conditions or abrupt transitions.
	const timer = setTimeout(() => {
	router.replace("/peers");
	}, REDIRECT_DELAY_MS);