feat(api): add remote access pydantic schemas

backend/app/schemas/remote_access.py

@@ -0,0 +1,39 @@
+from pydantic import BaseModel, Field
+
+
+class WinboxSessionResponse(BaseModel):
+    tunnel_id: str
+    host: str = "127.0.0.1"
+    port: int
+    winbox_uri: str
+    idle_timeout_seconds: int = 300
+
+
+class SSHSessionRequest(BaseModel):
+    cols: int = Field(default=80, gt=0, le=500)
+    rows: int = Field(default=24, gt=0, le=200)
+
+
+class SSHSessionResponse(BaseModel):
+    token: str
+    websocket_url: str
+    idle_timeout_seconds: int = 900
+
+
+class TunnelStatusItem(BaseModel):
+    tunnel_id: str
+    local_port: int
+    active_conns: int
+    idle_seconds: int
+    created_at: str
+
+
+class SSHSessionStatusItem(BaseModel):
+    session_id: str
+    idle_seconds: int
+    created_at: str
+
+
+class ActiveSessionsResponse(BaseModel):
+    winbox_tunnels: list[TunnelStatusItem] = []
+    ssh_sessions: list[SSHSessionStatusItem] = []