Create JSONResponse for "Śledzone trasy"

I'll (FE) be ready to reveive `_JSON_ ` from backend.
I don't know whether it would apply to travels being searched.

NOTE: `?` in key - `key?:` means that value may be null.
NOTE2: We may have different definitions of routes / segments so ask me if you need
NOTE3: Routes can have many segments, segments are assigned to one route only.

Get Followed (?) routes (or something like that), followed != saved!!!

_Route Example:_
```
{
id: number
name: string,
routeStart: string, # Budryka 2, Kraków
routeDestination: string, # Dworzec Główny, Tarnów
startDate: whatever suits you, # 13:23, 06.10.2025
endDate; -||-,
estimatedTime: string, # 01:10h; 38 minut
problem: boolean
level?: 1 | 2
}
```

For something like: Get segments by routeId (whatever you call it)
_Segments Example:_
```
{
id: number, # preffered: 1, 2, 3 - will be shown to user
routeId: number
from: string,
to: string,
type: "Foot" | "Bus" | "Tram" | "Train",
estimatedTime: string, # 11 minut, 03:15h etc
busLine?: string,
trainName?: string, # IC 3213 Żeromski
tramLine?: string
problem: boolean
level?: 1 | 2
}

}
```

Start by identifying the backend's existing response patterns and the entry points for followed routes and route segments. Clarify whether searched trips are included and agree on route, segment, date, and optional-field definitions; done means JSON responses expose the agreed followed-route and segment data.

索引モデルが issue の本文から書いたものです。