ban gemini: quarantine 10 SDK-using scripts under scripts/_archived-gemini/

User reported a ~ Google Gemini bill against an expected ~ budget.
Permanent ban on Gemini for this project — all LLM inference goes through
claude -p --model sonnet (CLAUDE_CODE_OAUTH_TOKEN) or OPENROUTER_API_KEY as
fallback. The 10 scripts in scripts/ that import google-genai/-generativeai
are moved under scripts/_archived-gemini/ with a DO-NOT-RUN README. Project
memory updated (feedback-no-gemini-ever.md) and the older reference note that
recommended gemini-3.1-pro-preview is revoked.

scripts/_archived-gemini/README.md

@@ -0,0 +1,12 @@
+# Quarantine — DO NOT RUN
+
+These scripts use the Google Gemini SDK. **Gemini is permanently banned on this
+project** after a billing incident (~$200 charged vs ~$10 expected, May 2026).
+
+Anything that needs LLM inference here goes through **Claude Code OAuth (Sonnet)**
+via `claude -p` subprocess, OR `OPENROUTER_API_KEY` as fallback. Never Gemini.
+
+Kept here for archaeology only — to re-enable, port to `claude -p --model sonnet`
+with `--output-format json` and add an explicit `--max-cost` cap.
+
+See `~/.claude/projects/-Users-guto-ufo/memory/feedback-no-gemini-ever.md`.