Plain `say` templates need placeholder naming, and an argument named `id` breaks the descriptor

[k0d13]

Two related gaps in @saykit/transform-js, both about the flat descriptor say.call receives.

An argument named id clobbers the message id

generateSayCallExpression (packages/transform-js/src/generator.ts:14-17) builds { id, ...values } as one object literal, so an argument that happens to be called id emits a duplicate key and wins:

say`Hi ${id} and ${name}`       // → say.call({ id: "sF5gu7", id: id, name: name })
say({ id: "greet" })`Hi ${id}`  // → say.call({ id: "greet", id: id })

descriptor.id is then the runtime value of the variable, so the lookup in Say#call (packages/integration/src/runtime.ts:243) misses and throws Message for <value> is not a string. It fails at runtime, in whatever locale happens to be active, with no build-time signal.

@saykit/transform-jsx no longer has this: as of #66 it compiles every value behind an underscore (_id={id}, _0={<u/>}) and the runtime strips one underscore back off, so Say's own props and the message's values live in separate namespaces and no name is reserved. say.call has no equivalent separation — the fix is a decision about its contract, either the same underscore convention with the runtime unprefixing, or splitting the id out of the values object (call(id, values)).

No way to name a placeholder in a plain say template

#66 added say-tag for JSX:

<Say>Signed in as <strong say-tag="bold">{user}</strong></Say>
// → Signed in as <bold>{user}</bold>

Plain templates have no equivalent, so their placeholders stay numbered and a translator gets <0> with nothing to go on. A placeholderLabel()-style macro was discussed in #61 and deliberately left out of #66's scope.

Worth doing together: whatever names a placeholder in a template has to agree with whatever fixes the descriptor namespace above.