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Implements docs/sdd/01-M-模型设计.md §1.0-1.14 as stdlib sqlite3 DDL in src/ (deployment/deploy_health_signal §1.15-1.16 are PH5/U-034, deliberately excluded). Covers all entities' fields, enum CHECK constraints, FKs, and the two non-trivial unique indexes (work_graph_run's per-(task_id,org_node) active-run partial index, artifact's (task_id,artifact_type,git_commit_sha) composite key). Per user decision (2026-07-30): bug_record.root_cause_category excludes 'core_engine' for now -- that value is PH5-scoped and development-plan.md assigns adding it to U-034, not U-001; a test locks this in. 14 stdlib unittest cases in src/test_schema.py cover table creation and the Done criterion's named constraint classes (unique/FK/enum), all passing. Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>