Refactor all database drivers, query execution, schema operations, and
business logic into a shared `dbx-core` crate. The Tauri desktop app
becomes a thin shell delegating to dbx-core, enabling future web and
CLI frontends to reuse the same core.
- PostgreSQL: rewrite column query from information_schema to pg_attribute for accurate type info via format_type(atttypid, atttypmod); extract character_maximum_length from atttypmod for varchar/bpchar; fix execute_query with persistent(false) and empty result fallback
- SQL Server: reconstruct column types with precision (varchar(max), decimal(p,s), datetime2(p)); stop dividing nvarchar/nchar CHARACTER_MAXIMUM_LENGTH by 2
- MySQL: use COLUMN_TYPE instead of DATA_TYPE for full type definitions; add CHARACTER_MAXIMUM_LENGTH; fix ONLY_FULL_GROUP_BY with MIN(NON_UNIQUE)
- Oracle: add CHAR_LENGTH/DATA_LENGTH for column type precision; fix INDEX_OWNER join to prevent cartesian product
- SQLite: fix PRAGMA injection via double-quote escaping; detect primary key indexes via origin column
- Add rust_decimal feature to sqlx and tiberius for proper Decimal type handling
- Fix try_get_unchecked<String> causing NULL or garbled output for numeric types
- Add numeric_precision and numeric_scale to ColumnInfo for all database drivers
- Update frontend to display precision (e.g., numeric(20,6)) in column headers
- Fix typeColorClass to handle type names with precision suffix
Root cause: PostgreSQL binary protocol sends NUMERIC as PgNumeric binary format,
not UTF-8 text. try_get_unchecked<String> attempted to decode binary bytes as UTF-8,
causing decode failures (NULL) or garbage characters (乱码).
t8y2