feat: self-serve signup Phase 2 (frontend cutover) (#162)

Co-authored-by: Michael Chihlas <michael@resolutionflow.com>
Co-committed-by: Michael Chihlas <michael@resolutionflow.com>

backend/app/schemas/config.py

@@ -0,0 +1,18 @@
+"""Pydantic schemas for public runtime configuration."""
+
+from __future__ import annotations
+
+from typing import List
+
+from pydantic import BaseModel
+
+
+class PublicConfigResponse(BaseModel):
+    """Runtime feature flags + OAuth provider list exposed to anonymous clients.
+
+    Read once by the frontend at app load to decide whether to render the
+    self-serve signup flow and which OAuth buttons to show.
+    """
+
+    self_serve_enabled: bool
+    oauth_providers: List[str]