550ddcba83
Windows cmd.exe always exports PROMPT (its prompt template, default "$P$G")
into a child's environment. The engine's `getenv("PROMPT")` picked that up, so
running `glm.exe` from cmd for the oracle self-test instead entered text-
generation mode — loading a tokenizer the tiny model doesn't ship and failing
with "tokenizer.json: No such file". PowerShell has no PROMPT env var, so it
worked there (galmok's 32/32) but not in cmd — same command, different shell.
New coli_user_prompt(): honors COLI_PROMPT everywhere, and on Windows ignores a
PROMPT that carries cmd's $-metacodes ($P,$G,...) — a real prompt has none. cmd
users can still pass a prompt via COLI_PROMPT or a non-$ PROMPT. Verified: $P$G
-> oracle mode, "Explain recursion" -> honored, COLI_PROMPT -> honored.
Third native-Windows bug surfaced by a from-scratch main download (after the
-lpsapi link fix and the bilingual oracle message).
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>