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/src/simplex_chat/_version.py

@@ -0,0 +1,9 @@
+"""Single source of truth for both the Python package version and the
+simplex-chat-libs release tag we depend on.
+
+Bump both together for normal releases. For wrapper-only fixes use a PEP 440
+post-release: __version__ = "6.5.1.post1", LIBS_VERSION unchanged.
+"""
+
+__version__ = "6.5.1"  # PEP 440 — read by hatchling for wheel metadata
+LIBS_VERSION = "6.5.1"  # simplex-chat-libs release tag (no 'v' prefix)