fix: docs(site): document the whole instrument catalog (#27)

The site rendered examples for three voices — gameBoyDmg, gbaDirectSound, basicOsc — and
said nothing about the other thirty. The catalog page now covers all 33: label,
description, every parameter with its default, and the factory presets where they exist.

Generated from generatorCatalog() and defaultParamsForGeneratorId() rather than written by
hand, so it cannot drift from the code. Presets come from the app that authored them.

packages/synths also had no presence on the site at all — site/build.mjs listed
packages/player explicitly and never mentioned it, so the package README did not render.
It has an Instruments section now.

Verified: site builds, /synths/ and /synths/catalog/ render, all 33 ids appear on the
page, 26 preset blocks, and the catalog is in the sidebar.

Author: spacedevin