c0f5626787
Advanced-mode SQL CREATE TABLE gains the constraints that need no new internal table (the 4a.2 slice): - Grammar (sql_create_table.rs): column-level DEFAULT/CHECK and table-level UNIQUE(cols). DEFAULT is a literal or a *parenthesised* expression (standard SQL) — a bare sql_expr greedily eats a following NOT (NOT IN/LIKE/BETWEEN), breaking `DEFAULT 0 NOT NULL`; the parens bound it. CHECK is paren-bounded already. - Builder (ddl.rs): captures CHECK/DEFAULT raw SQL text by byte span (sql_expr builds no AST) via capture_parenthesised_span / capture_expr_span; routes single-column table UNIQUE into the column's flag and composite UNIQUE into unique_constraints. - Command/worker: ColumnSpec gains check_sql/default_sql (raw, preferred over the typed Expr/Value); Command::SqlCreateTable + Request + do_create_table gain unique_constraints; do_create_table emits raw CHECK/DEFAULT and composite UNIQUE clauses. - Round-trip (part D): ReadSchema/TableSchema gain unique_constraints; read_schema detects composite UNIQUE via PRAGMA index_list origin 'u' (single-column still folds to the column flag); schema_to_ddl emits them; YAML RawTable/write_table round-trips (optional-on-read). CHECK round-trips via __rdbms_playground_columns.check_expr, DEFAULT via PRAGMA table_info — no new metadata table. Table-level/multi-column CHECK remains 4a.3 (rejected "not yet supported"); FK is 4b. Tests: +7 builder (raw-text capture incl. the DEFAULT 0 NOT NULL boundary the fix was found by; single/composite UNIQUE routing) and +4 Tier-3 (CHECK enforced, DEFAULT applied, composite UNIQUE enforced, and all three survive a rebuild — the part-D round-trip). 1752 pass / 0 fail / 1 ignored; clippy clean. Plan + requirements.md updated.