feat: Google OAuth prompt parameter and login OAuth error display

[HarshMN2345]

• Add dedicated googleOAuth.svelte modal with prompt picker in Advanced section
• Add googlePromptPicker.svelte: tag-based multi-select enforcing none exclusivity
• Wire prompt array through updateOAuth.ts to updateOAuth2Google SDK call
• Fix OIDC advanced param detection to URL-based logic (all URL params except wellKnownURL)
• Show OAuth failure URL error message on login page via onMount

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[greptile-apps]

Greptile Summary

This PR introduces a dedicated Google OAuth2 settings modal with a tag-based prompt picker (none, consent, select_account with none-exclusivity enforced), wires promptValues through updateOAuth.ts to the SDK call, reorders the Advanced accordion in the generic OIDC modal, and shows a hardcoded error notification on the login page when redirected back with a ?message parameter.

• googleOAuth.svelte and googlePromptPicker.svelte are new Google-specific components that replace the generic mainOAuth.svelte for the google and googleImagine providers; prompt state is initialised from the provider object via an untyped cast and compared order-independently via .sort().join(',').
• updateOAuth.ts adds an optional promptValues field with a safe ?? [] fallback, keeping all other providers unaffected.
• The login page onMount reflects a safe, hardcoded message string rather than the raw URL parameter value.

Confidence Score: 5/5

The change is well-scoped: the new Google component mirrors patterns from mainOAuth.svelte, the prompt array wiring is isolated to the Google SDK call, and the login page notification uses a hardcoded string rather than reflecting URL content.

All changed paths are additive or narrowly scoped. The prompt picker logic is straightforward, the updateOAuth.ts threading is non-breaking for all other providers, and the login page fix avoids user-controlled content in the notification. No defects were found that would affect data integrity or user-facing correctness.

googlePromptPicker.svelte uses Svelte 5 runes syntax while the rest of the provider files use Svelte 4 — worth aligning before the codebase fully migrates.

Important Files Changed

Filename	Overview
src/routes/(console)/project-[region]-[project]/auth/(providers)/googleOAuth.svelte	New Google-specific OAuth modal with prompt picker and write-only secret UX; initialises prompt from provider data via an untyped cast; otherwise consistent with mainOAuth.svelte patterns
src/routes/(console)/project-[region]-[project]/auth/(providers)/googlePromptPicker.svelte	Tag-based multi-select with correct none-exclusivity logic; mixes Svelte 5 runes props with Svelte 4 on:click event directive
src/routes/(console)/project-[region]-[project]/auth/updateOAuth.ts	Adds optional promptValues to Args and threads it through to updateOAuth2Google with a safe ?? [] fallback; no issues found
src/routes/(console)/project-[region]-[project]/auth/(providers)/mainOAuth.svelte	Moves Advanced accordion below the secret input section and updates isOidcAdvancedParam to a URL-substring heuristic (already discussed in prior review thread)
src/lib/stores/oauth-providers.ts	Swaps both google and googleImagine providers to use the new Google-specific component; straightforward substitution
src/routes/(public)/(guest)/login/+page.svelte	Adds onMount to show a hardcoded error notification when the ?message parameter is present after an OAuth redirect; does not reflect the URL value directly

_{Reviews (2): Last reviewed commit: "format" | Re-trigger Greptile}