feat: SORT ON <field>[/D] TO <newtable> (#8)

[DDecoene]

Closes #8.

What

Adds the dBASE III SORT command:

SORT ON <field>[/D] TO <newtable>

• Writes a sorted copy of the active table into a new table.
• /D → descending (default ascending).
• Honours the active SET FILTER.
• Errors when: no table in use, the field doesn't exist, or the target table already exists.

Approach — thin alias

After discussion, SORT is authentic dBASE III but largely redundant in WebBase-III's SQLite model (live indexes + ORDER BY already cover ordering). It's implemented thinly, over CREATE TABLE … AS SELECT … ORDER BY, rather than a faithful schema clone.

Accepted trade-off: the new table is a plain snapshot — column affinities are inferred and the source PK/constraints are not carried over. Noted in CHANGELOG. Spec: docs/superpowers/specs/2026-06-24-sort-to-design.md.

Changes

• src/interpreter/Lexer.ts — SORT keyword
• src/interpreter/Parser.ts — parseSort() + SORT AST node
• src/interpreter/Executor.ts — doSort() + HELP line
• tests/Session.test.ts — 2 parser + 5 integration tests
• README.md, CLAUDE.md — command-table rows
• package.json 0.6.2 → 0.6.3, CHANGELOG.md

Verification

• npm test → 172 passed
• npx tsc --noEmit → clean

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