Let a function node's own settings be edited

A python node's params reach process() as whatever its author put there,
but there was no way to put anything there: the settings form is built
from a type's declared schema, and a function node declares none.

Node types now say whether they take settings beyond their schema, and
the panel offers a key/value editor for the ones that do — named, typed
as text, number, on/off or JSON, and laid out like the port list beside
it. Rows are keyed by position rather than by name, so renaming a setting
does not remount the row and lose what was being typed into it.

Verified in the running app in both themes.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_011LF61rxW1FG5YCD2J9YqjY

NOTEPAD.md

@@ -74,6 +74,10 @@ Deferring because out of scope is fine, but don't mention deferring than.
   threshold. React Flow and Monaco are already lazy; a manualChunks split measured no better,
   so this needs route-level work on the shell rather than chunking config.
 
+- CHORE/INFRA: `bun run --filter frontend build` fails on this workspace with
+  `crypto.hash is not a function` — Vite 7 wants Node 20.12+ and the host has 18. The
+  Docker image builds fine, so it only bites local bundling; `bunx tsc` still type-checks.
+
 ## Blocked
 
 - FEAT/UI: a "Bug" icon on the node error bubble opening the logs panel at that node's