fix(platform): address round 2 review findings

docs/tests/web/smtp-error-sanitization.md

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+# Test Evidence: Sanitized SMTP failure feedback
+
+- **Test type:** Web
+- **Requirement IDs:** `INT-005`, `INT-008`
+- **Scenario IDs:** `AC-INT-002` (failed-draft browser boundary)
+- **Test class/method:** `com.lab.labtimesheet.feature.integration.controller.SmtpOnboardingWebIntegrationTest#failedSmtpTestRendersActionableFeedbackWithoutActivatingTheDraft`
+- **Implementation commit:** `pending`
+
+## Protected behavior
+
+An SMTP test failure renders fixed actionable guidance but never renders the external adapter's arbitrary diagnostic.
+The failed draft remains untested and cannot be activated.
+
+## Test method
+
+MockMvc saves a valid SMTP draft, configures the in-memory network adapter to throw a distinctive non-secret raw
+diagnostic, and submits the authenticated CSRF-protected test action. It checks the production controller and
+Thymeleaf response for the fixed message, absence of the raw diagnostic, and absence of the activation action.
+
+## Hand-derived expected result
+
+The response is HTTP 200 on `smtp/form`, contains the fixed operator message, omits the adapter diagnostic, and does
+not offer Activate SMTP.
+
+## RED
+
+**Command**
+
+```text
+export JAVA_HOME=/opt/homebrew/opt/openjdk@25
+export PATH="$JAVA_HOME/bin:$PATH"
+export DOCKER_HOST=unix:///Users/sechmachine/.orbstack/run/docker.sock
+./mvnw -Dtest=SmtpOnboardingWebIntegrationTest#failedSmtpTestRendersActionableFeedbackWithoutActivatingTheDraft test
+```
+
+**Observed result**
+
+```text
+Tests run: 1, Failures: 1, Errors: 0, Skipped: 0
+The fixed guidance was absent and the rendered smtpActionError contained the adapter's distinctive diagnostic.
+BUILD FAILURE
+PostgreSQL: 18.4
+```
+
+## GREEN
+
+**Command**
+
+```text
+./mvnw -Dtest=SmtpOnboardingWebIntegrationTest#failedSmtpTestRendersActionableFeedbackWithoutActivatingTheDraft test
+```
+
+**Observed result**
+
+```text
+Tests run: 1, Failures: 0, Errors: 0, Skipped: 0
+BUILD SUCCESS
+PostgreSQL: 18.4
+```
+
+## Affected suite
+
+**Command and result**
+
+```text
+./mvnw -Dtest=TimeConfigurationTest,BootstrapIntegrationTest,SmtpOnboardingWebIntegrationTest,AccountActivationIntegrationTest,AccountWebIntegrationTest,BootstrapOnboardingWebIntegrationTest,JavaMailSmtpProbeTest,SecurityResponseIntegrationTest test
+Tests run: 22, Failures: 0, Errors: 0, Skipped: 0
+BUILD SUCCESS
+PostgreSQL: 18.4
+```
+
+## External-test boundaries
+
+The SMTP adapter is in-memory, so this does not prove live server interoperability. The diagnostic is a deterministic
+non-secret fixture; no password, credential, or activation token is logged or recorded.