CI: set ``LDR_TEST_MODE=1`` on every test/scan workflow that starts a server or initialises the test database, so the intended fast SQLCipher KDF (``LDR_DB_CONFIG_KDF_ITERATIONS=1000``) is actually honoured. ``_get_min_kdf_iterations()`` deliberately ignores generic ``CI``/``TEST_ENV`` and only relaxes for ``PYTEST_CURRENT_TEST``/``LDR_TEST_MODE``; without the latter the requested 1000 was silently clamped to the production minimum (256000), making every DB open and the post-login background backup ~256× slower. Under contended CI runners that turned the backup into a multi-minute, GIL-holding stall that timed out release-gate UI shards (chat/settings navigations) — the failures seen on clean ``main`` while investigating #4430. Also renames the deprecated ``LDR_DB_KDF_ITERATIONS`` env var to its canonical ``LDR_DB_CONFIG_KDF_ITERATIONS`` across all six workflows (docker-tests, nuclei, owasp-zap-scan, playwright-webkit-tests, puppeteer-e2e-tests, docker-multiarch-test).
