@cipherstash/eql 4.0: ship the v3 and v4 bundles together and move Stack Encrypt's targets to v4 #1142

Background

@cipherstash/eql ships EQL's SQL bundle, along with the eql-bindings
crate, the docs and the postgres-eql image, all at one version. After #1141 the
build produces two bundles from one source.

Problem

1. Stack Encrypt's only producible type, TextEq, still writes eql_v3_*
   domains.
2. The new kinds have no EQL target.
3. Releasing v4 by bumping main and patching v3 from a branch would need a
   maintenance release path that doesn't exist. And npm-publish.mjs puts
   every stable release on latest, so a 3.x patch would move latest
   backwards.

Proposal

1. Publish @cipherstash/eql 4.0 with both bundles, and an exports entry for
   each. A SQL fix lands in both in one release. "4.0" means v4 is available,
   not that v3 is gone.
2. In eql-codegen, eql-domains and eql-bindings:
   • generate v4 targets;
   • move TextEq to v4;
   • delete the Stack Encrypt targets on eql_v3_* domains and their
     "producer profile" reason strings;
   • set the v4 payload's "v": 4;
   • keep the stack-encrypt:1: ciphertext prefix.
3. Make the non-text families producible in v4 (stashgen refuses every number, date and boolean EQL type — produce them in EQL v4 using ADR-0002's encodings #1130).
4. Regenerate Go's encrypt/eql/eql_gen.go.
5. Write docs/upgrading/v4.0.md: v4 is the v3 SQL with Stack Encrypt terms,
   and a column moves from v3 to v4 by re-encrypting it.
6. Add an @cipherstash/eql major changeset.

During the overlap with v3, cipherstash-client gets fixes only. New kinds and
domains are v4-only.

Needs #1140 on crates.io and #1141. Decided in ADR-0002 (#1139).