fix(rust): render columns in projection order

[thekevinbot]

Fixes #1170

SELECT path, ctime FROM './' printed ctime, path: Db::query collected each
row into a HashMap and threw away stmt.column_names(), so every renderer
re-derived its columns from row keys and got alphabetical order. --format json
had the same defect through serde_json's BTreeMap-backed objects.

The column order now travels with the rows. Db::query_ordered /
DirSQL::query_ordered return a QueryResult { columns, rows }; the CLI's
shared query pipeline serializes each row against columns (with
serde_json's preserve_order), and the table renderer takes the columns in
the order the rows carry them rather than sorting them into a BTreeSet.
query keeps its Vec<Row> signature, so Row, differ.rs and the SDK
bindings are untouched.

Scope is the Rust core + CLI. Python/TS parity is drift, tracked in PARITY.md
and filed as #1173 and #1174.

Red/green

The two test commits went up alone first. CI (Rust CI / Integration tests, run
35888793774) went red on the new integration test for exactly the asserted
reason:

test serialized_rows_follow_the_projection_order ... FAILED
panicked at packages/rust/tests/column_order.rs:56:5:
expected `size` before `basename`, got: [{"basename":"a.md","size":6}]

cargo test aborts at the first failing test binary, so column_order_e2e.rs
was not reached in that run; its red was confirmed locally on the same commit:

test the_table_header_follows_the_select_list ... FAILED
  left: ["basename", "size"]
 right: ["size", "basename"]
test json_keys_follow_the_select_list ... FAILED
expected `size` before `basename`, got: [{"basename":"a.md","size":6}]

Manual run

Built cargo build -p dirsql --features cli and ran it over a two-file temp dir:

$ dirsql "SELECT path, ctime FROM './' LIMIT 5" --format table
path  ctime
----  ----------
a.md  1790181167
b.md  1790181167

2 rows

$ dirsql "SELECT path, ctime, size FROM './' LIMIT 2" --format json
[{"path":"a.md","ctime":1790181167,"size":6},{"path":"b.md","ctime":1790181167,"size":10}]

E2E Verification

• Ran e2e suites locally for every affected SDK
• Python SDK e2e: pass
• TypeScript SDK e2e: pass
• Rust core e2e (if applicable): pass
• packages/python/e2e-attestations/<branch>.json receipt written if packages/python changed (just e2e-attest-python)
• packages/ts/e2e-attestations/<branch>.json receipt written if packages/ts changed (just e2e-attest-ts)
• Command(s) run: cargo test --manifest-path packages/rust/Cargo.toml --features cli --lib, ... --tests, just e2e-attest-python, just e2e-attest-ts, just preflight
• Result summary: rust unit 894 passed; rust integration + e2e all binaries green; python e2e 38 passed; ts e2e 17 passed (5 files); preflight 0 failing pairs (rust mutation: 11 mutants, all caught).

Changelog / Migrations

• Changelog fragment added under <root>/<pkg>/changelog.d/ for each changed package (packages/rust/changelog.d/2026-09-23-projection-column-order.md)
• Migration fragment added under <root>/<pkg>/migrations.d/ (packages/rust/migrations.d/2026-09-23-projection-column-order.md — output key order changes for consumers who relied on the alphabetical order)

Parity

Introduces drift: query_ordered / QueryResult exist in Rust only.
PARITY.md updated; follow-ups filed as #1173 (Python) and #1174 (TypeScript).