docs(examples): add pyproject.toml to rasa demo project

[itsarbit]

Summary

Ships the canonical Rasa Pro manifest alongside the bundled CALM demo at examples/integrations/rasa/rasa_project/, so users onboarding through the arksim Rasa integration get Rasa's blessed Poetry toolchain, the rasa-pro private GCP registry, and a pinned version out of the box.

• New: examples/integrations/rasa/rasa_project/pyproject.toml: Poetry build-system, package-mode = false, pins rasa-pro = 3.14.0 from the europe-west3 registry.
• Updated: integration README.md prerequisites now lead with poetry install, keeps uv pip / pip as standalone fallback.
• Changelog: [Unreleased] → Added entry referencing pyproject.toml #148.

Scope

Only the Rasa example subtree is touched. The root arksim pyproject.toml (hatchling + hatch-vcs) is unchanged, and no runtime code, CI, or tests are affected.

Test plan

• cd examples/integrations/rasa/rasa_project && poetry install resolves rasa-pro==3.14.0 from the Rasa registry (requires RASA_PRO_LICENSE / registry auth).
• rasa train && rasa run --enable-api still launches the demo assistant after a Poetry-based install.
• arksim simulate-evaluate config.yaml from the parent directory completes the four bundled scenarios.
• README renders correctly on GitHub.

Closes #148.

cc @profrodai, picked up your suggestion from #148. Renamed the package to arksim-rasa-calm-demo and set package-mode = false so it doesn't try to build as a distributable, but kept the registry block and version pin as you spec'd. Let me know if you'd prefer a different version or want toml swapped for something else in the dev group.

[itsarbit]

Smoke-tested end-to-end locally ✅

Ran the full PR test plan from a clean Poetry install:

Step	Result
poetry install (against rasa-pro registry)	✅ resolves rasa-pro==3.14.0, lockfile written
poetry run rasa train	✅ model trained at models/20260423-110321-exponential-taco.tar.gz
poetry run rasa run --enable-api	✅ server up on :5005
arksim simulate-evaluate config.yaml	✅ 12 conversations across 4 scenarios, 47s eval, HTML report generated

Follow-ups folded in (commit 7ea6bca)

1. language-data explicit pin. rasa-pro 3.14.0 imports language_data during domain-config validation but does not declare it transitively; a fresh poetry install && rasa train otherwise fails with ModuleNotFoundError: No module named 'language_data'. Added language-data = "*" to the deps with an inline comment explaining why. @profrodai, worth flagging upstream; the missing declaration in rasa-pro's install graph breaks the out-of-box DX for new users.
2. poetry.lock shipped. Matches Rasa's own rasa-calm-demo pattern and gives users reproducible installs. Narrowly exempted from the repo's 500KB check-added-large-files hook via a path-anchored regex (global policy unchanged).

[itsarbit]

Hey Rod, thanks again for #148. We smoke-tested the full install + train + serve + eval flow end-to-end and a few things surfaced that I'd love your read on before we finalize, since they're more your canon than ours.

1. Version pin. We kept rasa-pro = 3.14.0 exactly from your snippet. Is that the version Rasa currently recommends for new integration demos, or should we track something newer (3.14.x patch, 3.16.x, etc.)? Happy to follow whatever you'd tell a new customer to pin.

2. language-data workaround. On a clean poetry install against 3.14.0, rasa train fails with ModuleNotFoundError: No module named 'language_data' inside langcodes.display_name() (triggered by verify_config_language during domain validation). We added language-data = "*" as an explicit pin to unblock training. Is this a known issue on your side, or worth us filing against RasaHQ/rasa? Also curious whether it's already been patched in a later 3.14.x, since that would let us drop the workaround.

3. Shipping poetry.lock. We committed the lockfile on the assumption it matched rasa-calm-demo, but on a closer look your demo doesn't commit one. Happy to drop ours and match Rasa's convention if that's a deliberate choice. Any reason you'd prefer we keep it for this integration specifically?

4. Registry auth for the supplemental source. I linked users at Rasa's install guide for the first-time poetry config http-basic.rasa-pro ... setup rather than writing our own incantation. If there's a better page or a shorter command Rasa recommends, I'll point at that instead.

5. priority = "supplemental". We kept your exact field here. Noticed Poetry will prefer PyPI first for every non-rasa dep with supplemental; explicit would scope the index strictly to rasa-pro and avoid any typosquat risk. Worth tightening, or is supplemental intentional?

6. Framing. Package name is currently arksim-rasa-calm-demo with Arklex as sole author. Given this is a co-authored integration, happy to reframe as a joint artifact (rename the package, add a Rasa contributor to authors). Just let us know who on your side should be listed.

Everything arksim-side has been tightened on branch 8f6bb68 (README step ordering, poetry run prefixes, --cors local-only warning, expanded changelog).