Draw curves in the terminal, and stop waiting five seconds to hear

`space` ticks runs on the serve dashboard's table and `enter` compares them:
one metric in braille, five distinct hues, and the table of what actually
differs under it. Both halves are routes that already existed — the browser's
own comparison endpoint for the curves, the runs export for the table, whose
input columns are filtered to the ones that vary.

The palette is hue rather than the web's lightness ramp on purpose: five steps
of one brand hue collapse to a single colour on a 16-colour tty.

The screen also subscribes to the engine's event bus over the same websocket a
browser uses, so a run that starts and finishes inside a tick is seen rather
than only recorded. `a` lists what a run left behind and fetches it.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_014SmyLMSqcJQ8tUL2qLj21s

backend/pyproject.toml

@@ -72,6 +72,10 @@ dependencies = [
     "rich>=13",
     # `fluksio serve` opens a dashboard with it at a terminal.
     "textual>=1.0",
+    # That dashboard subscribes to the engine's event bus over the same socket
+    # the browser uses. It arrives under `fastapi[standard]` either way, and is
+    # named here because this code imports it.
+    "websockets>=13",
     # The encrypted-payload half of web push (RFC 8291). It brings only
     # cryptography, which is already here. `pywebpush` would do the signing and
     # the request too, at the cost of `requests` *and* `aiohttp` — two HTTP
@@ -185,7 +189,7 @@ ignore = [
 "fluksio/cli.py" = ["T201"]
 "fluksio/sdk/cli.py" = ["T201"]
 # What it prints is the line left in the terminal after the dashboard closes.
-"fluksio/tui.py" = ["T201"]
+"fluksio/tui/app.py" = ["T201"]
 # Node functions take `params` whether or not they use it — that is the
 # contract the engine calls them with.
 "fluksio/flow/nodes.py" = ["ARG001", "ARG002"]