simplex-chat-python: add python library (#6954)

* docs: simplex-chat-python design and implementation plan

* bots: Python wire types codegen

* simplex-chat-python: package scaffold

* simplex-chat-python: native libsimplex loader

* simplex-chat-python: async FFI wrappers

* simplex-chat-python: ChatApi with 49 api methods

* simplex-chat-python: Bot class with decorators and dispatch

* simplex-chat-python: install CLI, example bot, README

* simplex-chat-python: audit fixes

* bots: regenerate API docs and types

Catches up the markdown, TypeScript and Python codegen outputs with two
upstream schema changes:

- APIConnectPlan.connectionLink became optional (from sh/python-lib audit
  fixes); cmdString and EBNF syntax now reflect optional parameter.
- APIAddGroupRelays command and CRGroupRelaysAdded/CRGroupRelaysAddFailed
  responses added in #6917 (relay management). The TS and markdown outputs
  were regenerated when #6917 landed but the Python types module only got
  the new entries with this regeneration.

* core: refresh SQLite query plans after relay_inactive_at migration

The M20260507_relay_inactive_at migration (#6917 / #6952) shifted the
query plans that 'Save query plans' verifies. Regenerated via the test
that owns those snapshots; no behavioral change.

* bots: keep APIConnectPlan connectionLink as required parameter

The prior audit-fixes commit changed the syntax expression to `Optional ...`
because the Haskell field is `connectionLink :: Maybe AConnectionLink`.
That misrepresents the API contract: the `Maybe` is purely an internal
signal for link-parsing failure (the handler returns `CEInvalidConnReq`
on `Nothing`), not API-level optionality. Callers MUST always pass a
connection link.

Revert the syntax expression to `Param "connectionLink"` and add a
comment so the intent is preserved next time someone audits.

Regenerates COMMANDS.md, commands.ts and _commands.py to match.

packages/simplex-chat-python/README.md

@@ -0,0 +1,70 @@
+# SimpleX Chat Python library
+
+Python 3.11+ client for [SimpleX Chat](https://simplex.chat) bots. Equivalent to the [Node.js library](https://www.npmjs.com/package/simplex-chat).
+
+## Install
+
+```bash
+pip install simplex-chat
+```
+
+The native `libsimplex` is downloaded lazily on first use. To pre-fetch:
+
+```bash
+python -m simplex_chat install                     # sqlite (default)
+python -m simplex_chat install --backend postgres  # linux-x86_64 only
+```
+
+## Quick start
+
+```python
+import re
+from simplex_chat import Bot, BotProfile, Message, SqliteDb, TextMessage
+
+bot = Bot(
+    profile=BotProfile(display_name="Squaring bot"),
+    db=SqliteDb(file_prefix="./squaring_bot"),
+    welcome="Send me a number, I'll square it.",
+)
+
+@bot.on_message(content_type="text", text=re.compile(r"^-?\d+(\.\d+)?$"))
+async def square(msg: TextMessage) -> None:
+    n = float(msg.text or "0")
+    await msg.reply(f"{n} * {n} = {n * n}")
+
+@bot.on_message(content_type="text")
+async def fallback(msg: Message) -> None:
+    await msg.reply("Send me a number, like 7 or 3.14.")
+
+if __name__ == "__main__":
+    bot.run()
+```
+
+`bot.run()` blocks. The connection address is logged on startup — paste it into a SimpleX client to talk to the bot. `Ctrl+C` to stop.
+
+Three decorators: `@bot.on_message(...)`, `@bot.on_command(name)`, `@bot.on_event(tag)`. Message handlers are first-match-wins in registration order, so register specific filters first and catch-alls last.
+
+See [`examples/squaring_bot.py`](./examples/squaring_bot.py) for the full example.
+
+## Development
+
+```bash
+uv venv && source .venv/bin/activate
+uv pip install -e '.[dev]'
+ruff check && pyright && pytest tests/
+```
+
+Wire types under `src/simplex_chat/types/_*.py` are generated. Regenerate with `cabal test simplex-chat-test --test-options='--match Python'`.
+
+## Release
+
+Manual for now. Bump `_version.py:__version__`, build a wheel, upload to PyPI:
+
+```bash
+uv build --wheel
+uv publish --token "$PYPI_TOKEN"
+```
+
+## License
+
+[AGPL-3.0](./LICENSE)