fix ci linting and stellar/url asset config

[miss-yusrah]

closes #568
closes #569
closes #574
closes #575

Summary

This PR addresses four small but important reliability issues across CI, frontend navigation state, and Stellar configuration.

Changes

• add enforced backend linting in CI and a new frontend lint job
• add minimal frontend ESLint setup and lockfile updates so npm run lint works in CI
• sync TransactionHistory pagination with the page query param and restore state on browser back/forward navigation
• move backend Soroban network passphrase selection to env-driven config and validate it against the configured RPC endpoint
• replace sender-key asset issuance in SendMoneyFlow with issuer addresses from frontend env config

Env updates

Backend:

• SOROBAN_RPC_URL
• NETWORK_PASSPHRASE

Frontend:

• VITE_USDC_ISSUER
• VITE_EURC_ISSUER

Verification

• passed: backend npm test -- src/__tests__/stellar-network.test.ts
• frontend lint now executes, but existing unrelated frontend lint/test issues still remain in the repo and were not cleaned up in this change

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