Remove case insensitivity from asset code

[philipliu]

What

This PR makes the asset codes case sensitive everywhere in the codebase. Since assets that are enabled by default, and assets added through the asset API are uppercased before being persisted, disbursements with these assets should not break from upgrading. However, if assets with lowercase asset codes were added to the database, existing disbursements will break. This is considered an edge case, and we should note that the user should audit their assets table and fix any assets before upgrading.

Detect problematic assets:

SELECT id, code, issuer FROM assets WHERE code != UPPER(code);  

Fix problematic assets:

UPDATE assets SET code = UPPER(code) WHERE code != UPPER(code);

Why

Stellar asset codes are case sensitive, so we shouldn't be uppercasing asset codes.

Known limitations

N/A

Checklist

• Title follows SDP-1234: Add new feature or Chore: Refactor package xyz format. The Jira ticket code was included if available.
• PR has a focused scope and doesn't mix features with refactoring
• Tests are included (if applicable)
• CHANGELOG.md is updated (if applicable)
• CONFIG/SECRETS changes are updated in helmcharts and deployments (if applicable)
• Preview deployment works as expected
• Ready for production

[stellar-jenkins]

stellar-disbursement-platform-backend-preview is available here:
SDP: https://sdp-backend-pr967.previews.kube001.services.stellar-ops.com/health
AP: https://sdp-ap-pr967.previews.kube001.services.stellar-ops.com/health
Frontend: https://sdp-backend-dashboard-pr967.previews.kube001.services.stellar-ops.com

[stellar-jenkins]

stellar-disbursement-platform-backend-preview is available here:
SDP: https://sdp-backend-pr967.previews.kube001.services.stellar-ops.com/health
AP: https://sdp-ap-pr967.previews.kube001.services.stellar-ops.com/health
Frontend: https://sdp-backend-dashboard-pr967.previews.kube001.services.stellar-ops.com

[Copilot]

Pull request overview

This PR removes case-insensitive comparisons for asset codes throughout the codebase, making them case-sensitive to align with Stellar's asset code standards. The changes replace strings.ToUpper() and strings.EqualFold() calls with direct equality checks, and introduce a new constant XLMAssetCodeAlias for the "NATIVE" alias. Only uppercase "XLM" and "NATIVE" are now recognized as native asset codes.

Key changes:

• Removed case-insensitive string operations (ToUpper(), EqualFold()) from asset code comparisons
• Added XLMAssetCodeAlias constant with value "NATIVE" alongside existing XLMAssetCode ("XLM")
• Updated all native asset checks to explicitly compare against both "XLM" and "NATIVE" constants

Reviewed changes

Copilot reviewed 13 out of 13 changed files in this pull request and generated 3 comments.

Show a summary per file

File	Description
internal/services/assets/assets_pubnet.go	Added XLMAssetCodeAlias constant for "NATIVE"
internal/data/assets.go	Replaced case-insensitive comparisons with case-sensitive equality checks for asset codes
internal/data/assets_test.go	Updated test cases to verify case-sensitive behavior
internal/data/fixtures.go	Updated fixture creation to check for both "XLM" and "NATIVE" explicitly
internal/transactionsubmission/transaction_worker.go	Replaced case-insensitive XLM check with explicit constant comparisons
internal/transactionsubmission/transaction_worker_test.go	Updated test to use asset constants instead of case-insensitive comparison
internal/transactionsubmission/services/horizon.go	Removed uppercasing from asset ID formatting
internal/services/payment_to_submitter_service.go	Updated payment validation to use case-sensitive asset code checks
internal/services/send_receiver_wallets_invite_service.go	Updated native asset detection to use exact constant matches
internal/services/send_receiver_wallets_invite_service_test.go	Added test cases for case-sensitive asset code behavior
internal/serve/httphandler/assets_handler.go	Removed uppercasing from asset creation and updated native asset checks
internal/serve/validators/wallet_validator.go	Updated asset type inference to use case-sensitive comparisons
internal/serve/validators/wallet_validator_test.go	Updated tests to verify case-sensitive asset code handling

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[stellar-jenkins]

stellar-disbursement-platform-backend-preview is available here:
SDP: https://sdp-backend-pr967.previews.kube001.services.stellar-ops.com/health
AP: https://sdp-ap-pr967.previews.kube001.services.stellar-ops.com/health
Frontend: https://sdp-backend-dashboard-pr967.previews.kube001.services.stellar-ops.com

[stellar-jenkins]

stellar-disbursement-platform-backend-preview is available here:
SDP: https://sdp-backend-pr967.previews.kube001.services.stellar-ops.com/health
AP: https://sdp-ap-pr967.previews.kube001.services.stellar-ops.com/health
Frontend: https://sdp-backend-dashboard-pr967.previews.kube001.services.stellar-ops.com

[marwen-abid]

LGTM! Thank you for being thorough with the fix.