Defer interaction replies to avoid timeouts and add payment/support flows

[Ignius14]

Motivation

• Prevent interaction timeout errors by deferring replies for button and modal handlers.
• Provide a complete buy/support workflow including payment monitoring, QR generation, and webhook delivery.
• Expose admin commands to manage pricing and confirm payments and make panels easy to create.
• Ship a localized startup tutorial and example .env so operators can configure and run the bot.

Description

• Updated src/Events/interactionCreate.js to call deferReply({ ephemeral: true }) for buy/payment and modal flows and to use editReply for follow-up messages.
• Added services: src/Services/paymentMonitor.js, pricingService.js, qrService.js, buyRequestStore.js, and buyPanelService.js to handle rate fetching, payment registration/checking, QR generation, and buy-panel embedding.
• Added commands and constants: src/Commands/tickets/buy-panel.js, panel-support.js, src/Commands/admin/setprice.js, confirm-payment.js, and src/Constants/customIds.js, plus config updates in src/Base/config.js and a .env example.
• Misc: added index.js, updated package.json (added qrcode and a test script), included a Lithuanian startup section in README.md, and included tests/pricingService.test.js covering pricingService behavior.

Testing

• Added unit tests tests/pricingService.test.js for getLiveRates, getPriceEur, and setPriceEur.
• No automated tests were executed as part of this change (tests were added but not run).
• Basic lint/format scripts remain available via npm run lint and npm run format but were not executed.
• Manual runtime validation was not recorded in automated test output.

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Codex Task