feat: implement OpenAI-compatible Realtime API with authentication and management features

- Added support for public Realtime API, including new routes for managing API keys and handling WebRTC connections.
- Introduced RealtimeApiKey model and associated CRUD operations for admin management of API keys.
- Implemented authentication mechanisms for API keys and client secrets.
- Enhanced environment configuration with new secrets for Realtime API.
- Created OpenAIRealtime session management and event processing for real-time interactions.
- Updated schemas and settings to accommodate new features and ensure compatibility with existing systems.

backend/migrations/versions/20260810_0018_add_realtime_api_keys.py

@@ -0,0 +1,58 @@
+"""add public Realtime API keys
+
+Revision ID: 20260810_0018
+Revises: 20260810_0017
+"""
+
+from __future__ import annotations
+
+from collections.abc import Sequence
+
+from alembic import op
+import sqlalchemy as sa
+
+
+revision: str = "20260810_0018"
+down_revision: str | Sequence[str] | None = "20260810_0017"
+branch_labels: str | Sequence[str] | None = None
+depends_on: str | Sequence[str] | None = None
+
+
+def upgrade() -> None:
+    op.create_table(
+        "realtime_api_keys",
+        sa.Column("id", sa.String(length=40), nullable=False),
+        sa.Column("name", sa.String(length=128), nullable=False),
+        sa.Column("key_prefix", sa.String(length=32), nullable=False),
+        sa.Column("key_hash", sa.String(length=64), nullable=False),
+        sa.Column("expires_at", sa.DateTime(timezone=True), nullable=True),
+        sa.Column("last_used_at", sa.DateTime(timezone=True), nullable=True),
+        sa.Column("revoked_at", sa.DateTime(timezone=True), nullable=True),
+        sa.Column(
+            "created_at",
+            sa.DateTime(timezone=True),
+            server_default=sa.text("now()"),
+            nullable=False,
+        ),
+        sa.Column(
+            "updated_at",
+            sa.DateTime(timezone=True),
+            server_default=sa.text("now()"),
+            nullable=False,
+        ),
+        sa.PrimaryKeyConstraint("id"),
+    )
+    op.create_index(
+        "ix_realtime_api_keys_key_prefix",
+        "realtime_api_keys",
+        ["key_prefix"],
+        unique=True,
+    )
+
+
+def downgrade() -> None:
+    op.drop_index(
+        "ix_realtime_api_keys_key_prefix",
+        table_name="realtime_api_keys",
+    )
+    op.drop_table("realtime_api_keys")