feat: add county map popup on city click

[Copilot]

When a city is clicked, display a popup showing its county (ilçe) map. Feature is opt-in via prop and county data must be explicitly imported to avoid bundle bloat.

Changes

New Component

• CountyMapPopup: Modal overlay with interactive county SVG, supports hover/click/tooltips, includes ARIA attributes and ESC key handling

New Props

• showCountyMapOnClick: Enable county map feature (default: false)
• countyData: Record of county data keyed by city ID
• countyMapWrapper: Custom wrapper for popup styling
• onCountyClick: Callback with county and city parameters

Data Structure

• CountyType: { id, name, path }
• CountyData: { cityId, cityName, counties }
• Sample data for Istanbul, Ankara, Izmir exported separately at turkey-map-react/lib/data/counties

Usage

import TurkeyMap from 'turkey-map-react';
import { istanbulCounties } from 'turkey-map-react/lib/data/counties';

<TurkeyMap 
  showCountyMapOnClick={true}
  countyData={{ istanbul: istanbulCounties }}
  onCountyClick={(county, city) => {
    console.log(`Clicked ${county.name} in ${city.name}`);
  }}
/>

Note: Sample county data uses placeholder rectangular paths. Production use requires real geographic SVG data.

Original prompt

---

This section details on the original issue you should resolve

<issue_title>County Map When A City is Clicked </issue_title>
<issue_description>### Introduction

When a city is clicked on the map there is no default behavior as the version of "v2.0.3". For majority of use cases can cover county base actions.

When a city clicked, a county map of the city can be displayed on a popup. This behavior:

• can be enabled by a prop which is not present by default.
• can be customized via custom wrapper

County data (built-in or custom) has to be explicitly imported in order to reduce bundle size when not used.
Good example here: https://github.com/ogun/turkiye-svg-ilce-haritasi

Must Haves

• Built-in county list has to be provided.

Introduced In

v3.0.0</issue_description>

Comments on the Issue (you are @copilot in this section)

• Fixes County Map When A City is Clicked  #5

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