USAi is never defined and the 'nothing to get in advance' claim contradicts the hard abort #336

Part of #335

What's wrong

A first-time reader is told they need "nothing in advance," but the acquisition path performs a hard abort when no USAi key is present. Separately, the term "USAi" is used without ever being expanded or explained — only a bare console URL appears.

Evidence (file:line)

• README.md:53 — "Nothing to get in advance"
• acq.backends/common.sh:2137, 2170, 2174 — acq aborts when no key is present
• common.sh:96 — only the USAi console URL appears; the term "USAi" is never expanded or explained anywhere

Suggested fix

• Define "USAi" (and how to get access) on first mention.
• Reconcile the "nothing in advance" line with the key requirement — the default path does require a key, so the reader should be told up front.

Surfaced via an automated audit (Fable) against a public clone; validated against main 2026-08-19. AI-assisted (OpenCode).