NOTEPAD: drop what is done, correct what was never true

A sweep against the code. Removed as resolved: the worker pool's `_running`
is keyed by (run, node) now, `WorkItem.kind` documents only the three kinds
that exist, `routeTree.gen.ts` matches its generator, and the host's Node is
well past the version the Vite 7 note was about. Removed as disproved: the
collector's redelivery branch is reachable — Redis reclaims an entry this
process is still running.

Corrected: the demo places six of the fifteen node types, not thirteen — the
count was the widget types. Narrowed to what is left: the header/config sync
now covers settings but only on an untouched scaffold and only one way; a
declared flow input is what the dashboard-input node asked for; the flow
boundary already refits the canvas where node ports do not.

The Playwright hazard is not resolved — both names still resolve to
production — and the fix as written is incomplete: `VITE_API_URL` has to be
overridden to `http://` or every setup call fails the TLS handshake.

Also: one `asText` instead of two, and the queue docstring no longer refers
to a node item that never existed.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01NUb8YpL2s3gmN9WTACTt4q

backend/app/flow/queue.py

@@ -43,7 +43,7 @@ class WorkItem:
         downstream; ``flush`` lets out what a node's rate limits held back;
         ``run`` is a whole batch run, and carries only its id.
     :param node: The node the item is about — the source for a cascade, the
-        target for a node item.
+        one whose rate limits are released for a flush.
     :param flow: The flow that node belongs to, so gating needs no lookup.
     :param outputs: What the source node emitted (cascade only).
     :param cause: Where the work came from, for logs and debugging.