fix: show real OAuth error on failure relay page

[ChiragAgg5k]

What does this PR do?

The OAuth failure relay page previously treated a missing project query param as "Missing redirect URL", even when an error payload was present (e.g. user_already_exists). This shows the real error message/type when error is present, and only falls back to the missing-redirect copy when neither project nor a parseable error exists.

Test Plan

1. Open /console/auth/oauth2/failure?error=%7B%22message%22%3A%22User%20already%20exists%22%2C%22type%22%3A%22user_already_exists%22%2C%22code%22%3A409%7D without project.
2. Confirm the page title is "Login failed" and the message shows "User already exists".
3. Open /console/auth/oauth2/failure with no params and confirm the existing "Missing redirect URL" copy still appears.
4. With project present, confirm the deep-link redirect behavior is unchanged.

Related PRs and Issues

• Related API: fix: include project on OAuth failure redirect appwrite#12976
• Google OAuth seems broken especially on iPadOS appwrite#12936

[greptile-apps]

Greptile Summary

Updates the OAuth failure relay to display an available OAuth error instead of missing-redirect guidance.

• Parses the error query parameter and renders its message and type when no project callback is available.
• Preserves the existing missing-redirect state when neither a project nor an error is present.
• Updates dependency overrides and the Bun lockfile for brace-expansion and postcss.

Confidence Score: 5/5

The PR appears safe to merge.

No blocking failures remain.

Important Files Changed

Filename	Overview
src/routes/(public)/auth/oauth2/failure/+page.svelte	Parses OAuth failure details from the query string and conditionally renders them when the custom-scheme redirect cannot proceed.
package.json	Raises the brace-expansion override and adds a postcss override.
bun.lock	Resolves the updated brace-expansion and postcss overrides, including postcss's nanoid dependency.

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