Put the deployment-only dependencies behind a server extra

A data-science environment installing fluksio waited for lxml, aiohttp and
the rest of a connector stack it has nothing to talk to. Outbound mail,
error reporting and the MQTT and InfluxDB clients moved to
`fluksio[server]`, which the image installs; each import is guarded and
names the extra. `tenacity` had no import site at all and is gone.

23 fewer packages and the compiled ones among them — a bare `pip install
fluksio` still serves, runs every python node, and registers the mqtt and
influxdb node types, which only need the library when one is actually
built. sentry-sdk arrives anyway underneath `fastapi[standard]`; what
changed there is that nothing of ours requires it.

The dev environment keeps every extra: the suite exercises the connectors
and strict mypy checks their call sites.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_019Hra4ndWMCLU5F3KjUuVAc

backend/fluksio/sdk/cli.py

@@ -485,14 +485,14 @@ def _params(definition: dict[str, Any], rest: list[str]) -> dict[str, Any]:
             f"{', '.join(sorted(types)) or 'none'}){hint}"
         )
     params: dict[str, Any] = {}
-    for name, value in raw.items():
-        if value is True:
-            params[name] = True
+    for key, written in raw.items():
+        if isinstance(written, bool):
+            params[key] = written
             continue
         try:
-            params[name] = _coerce(value, types[name])
+            params[key] = _coerce(written, types[key])
         except ValueError as exc:
-            raise SyncError(f"'{name}' takes {types[name]}: {exc}") from exc
+            raise SyncError(f"'{key}' takes {types[key]}: {exc}") from exc
     return params