feat: prep archastro-sdk for PyPI — namespace phx_channel + enrich metadata

[calvin-archastro]

Summary

• Move src/phx_channel/ → src/archastro/phx_channel/ so the distribution publishes a single top-level archastro package on PyPI (no squatting a generic phx_channel module).
• Enrich pyproject.toml for PyPI: authors, license, classifiers, urls, optional-deps dev, wheel excludes tests.
• Regenerate channel classes + contract tests from @archastro/sdk-generator@0.1.4, which emits the new namespace natively. Also picks up the latest ArchAstro/archastro-openapi@main spec.

Import changes (public API)

# before
from phx_channel import Socket, HarnessServiceClient
from phx_channel.channel import ChannelError

# after
from archastro.phx_channel import Socket, HarnessServiceClient
from archastro.phx_channel.channel import ChannelError

Logger name also renamed: "phx_channel" → "archastro.phx_channel".

pyproject.toml

• license = { file = "LICENSE" } (MIT, added separately to main as fbe4aab)
• authors, keywords, trove classifiers, [project.urls]
• [project.optional-dependencies].dev so pip install -e ".[dev]" works without uv
• [tool.hatch.build.targets.wheel].packages = ["src/archastro"] + exclude = ["**/tests/**"] — tests don't ship to PyPI anymore

Spec drift

The regen also pulled in the current platform spec from main. Besides the namespace rename, you'll see:

• New: activity_feed + invites resources and their contract tests
• Removed: types/{chat,members,orgs,reactions,schedules,system}.py (collapsed/renamed upstream)
• Changed: a lot of existing resource body signatures to match the current spec

I considered splitting these but they're genuinely coupled — the regen script is the mechanism that brings both the namespace change and the spec into the repo.

Test plan

• uv run pytest tests/test_http_client.py src/archastro/phx_channel/tests/test_unit.py — 45/45
• uv run pytest tests/harness — 6/6
• uv run pytest tests/contract (REST) — 670/670
• ARCHASTRO_RUN_CHANNEL_CONTRACT_TESTS=1 uv run pytest tests/contract/channels — 51/51
• uv run ruff check && uv run ruff format --check — clean
• uv build — produces archastro_sdk-0.1.0-py3-none-any.whl with archastro/ + archastro/phx_channel/, LICENSE in dist-info/licenses/, no test files

Follow-ups (not in this PR)

• Dry-run publish to TestPyPI before shipping 0.1.0 to prod.

🤖 Generated with Claude Code