Say what each dependency is for, and stop crediting fastapi for rich

The list read as a set of independent choices with two comments on it, one
of which was wrong: rich is not here "underneath fastapi's CLI" any more, it
is what textual is built on and what `fluksio status` imports directly.

Each line now says what imports it. The four that look redundant —
python-multipart, email-validator, jinja2, httpx — are also inside
`fastapi[standard]`, so they install nothing extra; they stay because the
code imports them directly and that should not rest on somebody else's
extra keeping its contents. email-validator in particular cannot move to
the server extra: `EmailStr` is on the user model, read on every start,
whether or not mail is ever sent.

Comments only. The resolved lock is byte-identical.

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

backend/fluksio/sdk/cli.py

@@ -644,8 +644,8 @@ def cmd_run(args: argparse.Namespace, rest: list[str]) -> int:
 # Status
 #
 # The home screen's top half, in a terminal: how the engine is, what each flow
-# is doing, and what failed recently. Drawn with rich, which is already here
-# under fastapi's own CLI.
+# is doing, and what failed recently. Drawn with rich, which is what the serve
+# dashboard renders this same group into.
 # ---------------------------------------------------------------------------