Add source-name guard allowlist exit criteria plan

[RicheyWorks]

Summary

• Add docs/test-only source-name guard allowlist exit criteria plan.
• Link the new plan from adjacent allowlist/rule docs, README, reviewer trust map, and enterprise readiness audit.
• Add documentation guard test coverage for planning-only status, links, criteria, non-exit conditions, non-proving boundaries, and no ArchUnit dependency.

Verification

• mvn -B dependency:tree -Dincludes=org.apache.tomcat.embed
• mvn -q test -Dtest=SourceNameGuardAllowlistExitCriteriaPlanDocumentationTest,SourceNameGuardAllowlistLifecyclePlanDocumentationTest,SourceNameGuardAllowlistSamplePlanDocumentationTest,SourceNameGuardAllowlistReviewChecklistDocumentationTest,SourceNameGuardAllowlistDesignPlanDocumentationTest,SourceNameGuardRuleReviewChecklistDocumentationTest,SourceNameGuardRuleCatalogPlanDocumentationTest,SourceNameGuardReportAcceptanceCriteriaPlanDocumentationTest,SourceNameGuardReportSamplePlanDocumentationTest,SourceNameGuardReportReviewChecklistDocumentationTest,SourceNameGuardReportSchemaPlanDocumentationTest,SourceNameGuardDryRunDesignPlanDocumentationTest,SourceNameGuardReviewChecklistDocumentationTest,LaseSourceNameGuardFeasibilityPlanDocumentationTest,LaseNamingGuardInventoryDocumentationTest,LaseBoundaryNamingGuardPlanDocumentationTest,LasePackageBoundaryEnforcementPlanDocumentationTest,LaseBoundaryEnforcementInventoryDocumentationTest,LaseBoundaryArchitectureContractDocumentationTest,ExternalSignalPortDesignContractDocumentationTest,WorkloadProfileSignalMetadataDesignContractDocumentationTest,ThreeTierAdaptiveRoutingStrategyDocumentationTest,ReviewerTrustMapDocumentationTest,EnterpriseReadinessAuditDocumentationTest,ReadmeVisibilityDocumentationTest,EnterpriseLabProductAlignmentDocumentationTest
• mvn -q test
• mvn -q -DskipTests package
• mvn -B package
• git diff --check
• git diff --check origin/main...HEAD
• git diff --cached --check
• .\scripts\smoke\enterprise-lab-workflow.ps1 -Package

Scope and Safety

Docs/test-only. No src/main/java changes, no allowlist files, no JSON/YAML/TOML output, no source scanning, no report generation, no CI workflow changes, no PR comment/artifact behavior, no runtime naming enforcement, no source-name guard enforcement, no package-boundary enforcement, no ArchUnit or Maven build changes, and no production behavior changes.