docs(app-shell): the flow canvas draft node becomes a real notify node

The "Visual flow canvas" jsonc draft taught `{ "id": "email", "type":
"action", ... }`. `action` is not a flow node kind: it is absent from
`FlowNodeAction` (objectstack `packages/spec/src/automation/flow.zod.ts`,
20 members) and from the canvas's own 18-entry `NODE_PALETTE`, so a reader
copying the draft has the node refused when the type is checked against the
live action registry at `registerFlow()`.

`notify` is the replacement the spec itself names for the retired
`email`/`slack` dispatch branches (flow.zod.ts:38-45). `script`, the other
candidate, disqualifies itself: its `config.function` is REQUIRED, and this
draft node carries no `config` at all.

`notify` turns out to have required config too, so the one-word change alone
would have swapped one refusal for another: `NotifyConfigSchema` declares
`recipients` non-optional (io-node-config.zod.ts:186) and its superRefine
(:261, message at :299) refuses a node carrying neither `title` nor
`template`. The executor parses `node.config ?? {}` through that contract at
execute time (notify-node.ts:250, parse-config.ts:99), so a config-less
`notify` node is refused. The draft therefore gains exactly those two keys
and nothing else.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01611D6ZaRaMmwTNQmSbk8MH

Author: claude

packages/app-shell/README.md

@@ -392,7 +392,8 @@ Salesforce Flow Builder) instead of a flat step list. It is **dependency-free**
     { "id": "start", "type": "start", "label": "Start" },
     { "id": "decide", "type": "decision", "label": "Renew?",
       "ui": { "x": 220, "y": 180 } },   // optional persisted canvas position
-    { "id": "email", "type": "action", "label": "Send reminder" },
+    { "id": "email", "type": "notify", "label": "Send reminder",
+      "config": { "recipients": "{record.owner}", "title": "Renewal reminder" } },
     { "id": "end", "type": "end", "label": "End" }
   ],
   "edges": [