Allow manual triggering of builds without requiring a commit.

[gandalf-at-lerian]

Problem

Currently, to trigger a build for a specific service (e.g., ledger), a commit must be made directly in that service. When changes are made in dependent services (e.g., onboarding, transactions), the main service's build is not automatically triggered.

Real scenario

• Changes were made to onboarding and transactions
• Only the ledger service was enabled in the test environment
• The ledger build was not triggered because the changes didn't directly touch the ledger code
• The image was stuck at a previous tag while a newer one was already available
• Current workaround: add an arbitrary line to the target service's Dockerfile just to force the build

Desired solution

Have a way to manually trigger a service build without needing an artificial commit. Possible approaches:

• workflow_dispatch with target service input
• Trigger via PR comment or tag
• Manual button in GitHub Actions