At Solid 2.0.0-rc.22: let Solid reconcile keyed guess-source answers (drop landDraft merge) #64

Follow-up to #51 / #63.

#63 fixes #51 by merging each answer of a keyed source that takes a guess into its createOptimisticStore draft by key (landDraft in ref/compile/rt.ts, rt-web.ts, rt-server.ts, ref/oracle/lower.ts, marked TODO(Solid rc.22)). The cleaner fix is to return the keyed answer from the derive and let Solid reconcile it against the optimistic view, which is the path Solid designed for this.

That path can't ship yet. On the published 2.0.0-rc.21 (and our pin 2105ffb), it throws inside Solid, in both dev and prod. It broke S-store-7 in the compiled runner. Minimal repro:

const [rows] = createStore(async () => await answer, []);
const titles = createMemo(() => latest(() => rows.map(r => r.title).join(",")));
createRenderEffect(titles, v => console.log(v));
// answer resolves to [{ id: 1, title: "A" }]
// → TypeError: Cannot read properties of undefined (reading '_x') in holdStaging

Solid next already fixes this (it prints A at dba2aad: holdStaging handles a store key's node-less staging), so no Solid issue is needed.

When rc.22 is published:

• sh ref/scripts/solid-next.sh --latest (or pin the rc.22 commit) and rebuild
• runtime: @solidjs/signals, @solidjs/web, solid-js to ^2.0.0-rc.22 (dependencies + devDependencies)
• replace landDraft's keyed merge with returning the answer, keeping assignDraft for unkeyed answers (an unkeyed {} seed has not been tried with the return path)
• all runners green (interpreter, compiled, oracle, ssr, types), S-store-7 and S-affects-keyed in particular