0a974e89 - Set FAUCET_LOW_BALANCE_THRESHOLD in the e2e-stack API env

[Danswar]

EN:
The API container in e2e-stack no longer boots: its Configuration constructor validates FAUCET_LOW_BALANCE_THRESHOLD and throws when it is unset, so the process exits before Nest starts and up.sh times out after 540s waiting for api to be healthy. env/api.env never set that variable, so every full E2E run since that guard landed fails before a single Playwright test executes. This adds the variable next to the identical REALUNIT_W2W_GAS_LOW_BALANCE_THRESHOLD entry.

DE:
Der API-Container in e2e-stack bootet nicht mehr: Sein Configuration-Konstruktor validiert FAUCET_LOW_BALANCE_THRESHOLD und wirft, wenn die Variable fehlt, wodurch der Prozess vor dem Nest-Start abbricht und up.sh nach 540s auf einen gesunden api wartet. env/api.env hat diese Variable nie gesetzt, also scheitert seither jeder vollständige E2E-Lauf, bevor überhaupt ein Playwright-Test läuft. Dieser PR ergänzt die Variable direkt neben dem gleichartigen Eintrag REALUNIT_W2W_GAS_LOW_BALANCE_THRESHOLD.

Details

Observed failure

up.sh waits for the api service and then dumps the container log:

[e2e-stack] Waiting for service 'api' to become healthy (timeout 540s)...
[e2e-stack] ERROR: Timed out after 540s waiting for 'api' (last status: starting).
[e2e-stack] ERROR: API failed to become healthy. Recent API logs:
api-1  |             throw new Error('Missing FAUCET_LOW_BALANCE_THRESHOLD');
api-1  |     at new Configuration (/home/node/dist/src/config/config.js:62:1)
api-1  |     at GetConfig (/home/node/dist/src/config/config.js:60:12)

The throw happens while a module-level static initializer builds the config, i.e. during
require, so it is fatal for the process — the faucet feature itself is never reached.

Timeline

The last green full E2E run was at 2026-08-26T09:57Z. The guard was merged into the API at
10:45Z. Every full run after that point fails with the log above; none of them reach the
Playwright step.

Why this value

It is a tuning threshold in ETH, not a credential, and the guard only requires a finite value
greater than zero. No faucet wallet is funded in this hermetic stack, so the threshold is never
compared against a real balance. 0.05 mirrors REALUNIT_W2W_GAS_LOW_BALANCE_THRESHOLD, which
sits in the same block for the identical kind of guard, and matches the API's own
.env.example.

Scope

One variable plus a comment covering both threshold entries. No compose or script change.