Add IncludeSpecials toggle for station maps and Telegram bot

[Copilot]

Summary

Adds a toggle to show/hide special and historic stations on station maps, and a per-user setting in the Telegram bot to include special stations when searching for nearby stations.

Changes

Backend

• StationGrouping model: Added IncludeSpecials boolean property (defaults to false — existing behaviour preserved)
• User model: Added TelegramIncludeSpecials boolean property for the bot setting
• EF migration (20260515122447_AddIncludeSpecials): Adds both new columns with DEFAULT FALSE
• StationMapDTO: Exposes IncludeSpecials to the API
• MappingExtensions: Maps IncludeSpecials in SelectToStationMapDTO
• StationMapsController:
  • GetVisitedStations conditionally excludes special stations based on the per-map setting
  • PutMap / PostMap persist the IncludeSpecials field

Telegram bot (TelegramBotService)

• Location handler: Passes TelegramIncludeSpecials to the nearby-stations query
• Callback handler: Uses the user setting when calculating region visit percentages; disambiguates toggle_specials callbacks from station-ID callbacks
• Settings command: Handles /settings and the reply-keyboard "⚙️ Settings" button — shows current state with an inline toggle
• toggle_specials callback: Flips TelegramIncludeSpecials in the DB and updates the settings message in-place
• Reply keyboard: Updated to include "📍 Share your location" and "⚙️ Settings" rows for consistent access

Frontend (Angular)

• StationMap interface: added includeSpecials: boolean
• station-maps-edit dialog: new checkbox bound to includeSpecials via reactive form
• i18n: STATIONMAP.INCLUDESPECIALS key added in both en.json and nl.json

Behaviour

Context	Default	User control
Station map view	Specials hidden	Toggle per map in edit dialog
Telegram bot nearby search	Specials hidden	/settings → toggle inline button

All existing tests pass (15/15). Both backend and frontend build without errors.