src/guest-names.ts gives each anonymous viewer a tasteful colour-and-animal name, stable per browser, never held by two at once - module and test only #290

From #148.

Done:

• [ ] src/guest-names.ts has curated colour and nature-noun lists ("Teal Heron", "Amber Fox") and a colour for the dot. nameFor(browserId, inUse) is stable for the same id and never returns a name already in use.
• [ ] Tests: two ids get different names; the same id gets the same name again; every name comes from the lists; no random strings.
• [ ] No wiring into the page or the lobby. forge.json untouched. bun --cwd Software/so101 test passes.