fix: Read transaction service API key from the environment at call time

[Primata]

TransactionServiceApi.__init__ exposed SAFE_TRANSACTION_SERVICE_API_KEY
and SAFE_TRANSACTION_SERVICE_REQUEST_TIMEOUT as default argument values.
That has two consequences:

1. Default arguments are evaluated once, when the module is imported, so a
   value placed in the environment afterwards (a .env loader, a test
   fixture, a notebook) is never seen.
2. SafeBaseAPI.from_ethereum_client forwards api_key=None explicitly,
   and an explicit None overrides a default. Every caller that builds the
   client through from_ethereum_client therefore gets api_key=None
   regardless of the environment.

safe-cli uses from_ethereum_client, so it sends no Authorization
header and warns "you must set the following environment variable with
your API key" even when the variable is set. Requests silently fall back
to the unauthenticated rate limit.

Resolving both values inside the constructor body fixes all three cases
while keeping an explicitly passed argument authoritative.

Note one intentional behaviour change: passing api_key=None while the
environment variable is set now yields an authenticated client. That is
what from_ethereum_client needs, and it matches how an optional argument
usually reads, but it does mean None can no longer be used to force an
anonymous client when the variable is present.

Tests are added in a SimpleTestCase, since they need neither the
database nor network access, and they fail on main:

FAILED test_api_key_read_from_environment_at_call_time
FAILED test_api_key_from_environment_with_explicit_none
FAILED test_request_timeout_read_from_environment_at_call_time

[github-actions]

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[Copilot]

Pull request overview

This PR fixes TransactionServiceApi initialization so the API key and request timeout are resolved from environment variables at constructor call time (instead of import time), and so from_ethereum_client(..., api_key=None) no longer unintentionally disables env-based authentication. It also adds unit tests to lock in the intended precedence rules.

Changes:

• Resolve SAFE_TRANSACTION_SERVICE_API_KEY and SAFE_TRANSACTION_SERVICE_REQUEST_TIMEOUT inside TransactionServiceApi.__init__ instead of as default argument values.
• Add SimpleTestCase tests covering env-at-call-time behavior, explicit-argument precedence, and the from_ethereum_client forwarding case.

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 2 comments.

File	Description
safe_eth/safe/api/transaction_service_api/transaction_service_api.py	Moves env resolution into the constructor to avoid import-time default evaluation and api_key=None overriding env.
safe_eth/safe/tests/api/test_transaction_service_api.py	Adds SimpleTestCase tests validating API key/timeout env resolution and precedence behavior.

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[Copilot]

Pull request overview

Copilot reviewed 2 out of 2 changed files in this pull request and generated no new comments.