P9. Publish

Specification: [`07-python-bindings.md`](../blob/main/docs/specs/07-python-bindings.md) section 8.

Actually publish, to PyPI and to `modular-community`, with a README that says what firepanda does and what it does not do yet.

### Frame this correctly

At M3 there is no lazy engine, no optimizer and no parallel execution. What ships is an eager columnar frame with fast CSV, fast Parquet and fast group by. That is enough to be interesting and **it is not enough to be impressive**, and the milestone has to be framed that way internally so that a lukewarm reception is read correctly rather than treated as a signal about the project.

The README is part of that framing and is not marketing. A user who installs this and expects a pandas replacement will be disappointed by things that are on the roadmap, and the way to avoid that is to say so on the page they read first.

### Scope

- [ ] The README, with the conformance number from firepanda-compat rather than an adjective, and the list of what is not there yet
- [ ] The compatibility policy published, including the error classes, which are part of the public API because `except KeyError` breaks as surely as a signature does
- [ ] A version and a changelog entry that records the Mojo toolchain version, since the ABI is not stable within 1.x
- [ ] Published to PyPI
- [ ] Published to `modular-community`
- [ ] An install verified from PyPI on a machine that has never had the toolchain

### Blocked on

The runtime redistribution licence issue. Everything else in M3 can proceed without an answer to it. This cannot.

Start with section 8 of docs/specs/07-python-bindings.md, then review the README, compatibility policy, version metadata, and changelog locations referenced by the issue. Confirm the runtime redistribution licence is resolved before attempting publication. Done means the documented scope and compatibility policy are published, the toolchain version is recorded, both package destinations work, and a clean-machine PyPI install is verified.

Written by the indexing model from the issue text.