Make Unity AI Gateway governance demo more developer-friendly

[dmatrix]

What

Cleans up the unity_ai_gateway_governance demo so it's easier for a developer to read and run.

• README: cut marketing/filler language, fixed typos, and corrected the broken step numbering in the model-service setup (Acts 7/8 were mis-numbered as config steps). Kept the technical gotchas developers actually need — how a guardrail block looks, the PII post_call trap, denied requests never reaching the inference table, and per-provider response shapes.
• Notebook markdown cells: removed repetitive "solution" phrasing and marketing slop from the intro, fixed typos (Jail break, mau, Act 7 :), and tightened awkward headers. Also dropped a duplicated gw_client assignment in the agent-setup code cell.
• Dependencies: added a pyproject.toml so the README's uv sync step works (mlflow, requests, pandas, python-dotenv, openai, jupyter) — the demo dir previously had no dependency manifest.

Verification

• All notebook code cells compile; local modules parse; every imported symbol resolves.
• uv lock --dry-run resolves the new manifest with no conflicts.
• Demo author confirmed the notebook runs end-to-end with these changes.

This pull request and its description were written by Isaac.

[djliden]

Closing this as superseded — nothing here was rejected, and nothing on your branch was rewritten or force-pushed.

Why it couldn't be merged: main received the demo in #19 from the same source commit this branch started from (4543795). That makes README.md and ai_gateway_demo.ipynb conflict add/add even though each side is byte-identical to what the other branch replaced — main's copies are the versions this branch edits, so there was nothing to reconcile.

What I did instead: since you're out for a few weeks, I re-landed your change unchanged as #21 — commit 5a58d8b, authored by you, with a tree verified byte-identical to this branch's head (e2dcc5b). #21 is now merged into main (as cf12979), so the README cleanup, the notebook tidy-up, and the new pyproject.toml are all in.

If you'd rather this had gone another way, reopen it or ping me and we'll sort it out.