Add a global search, and stop the sidebar logo squeezing

`GET /api/v1/search/` hands the client one flat index of everything worth
jumping to — flows and the nodes inside them, dashboards and the widgets on
them, panels, secrets, modules, workers and alert channels — and cmdk matches
it in the browser, so results narrow while typing without a round trip per
keystroke. A node hit is the one thing no list endpoint could answer: it opens
its flow with that node in focus.

The panel is reached from **Search** above Documentation in the sidebar, or
⌘K anywhere. The flow canvas palette moves to ⌘P, being the narrower of the two.

The panels dialog gains an address (`/dashboards?panels`) so a panel hit has
somewhere to land, and the sidebar logo gets `shrink-0`: the rail's width
animates while the logo is already back, and a flex item short of room is
squeezed rather than clipped.

docs/code/connectors.md

@@ -54,7 +54,7 @@ Two things to know about this:
   make dev-frontend             # Vite on :5173
   ```
 
-Restart the backend and your node type appears in the add-node palette (⌘K),
+Restart the backend and your node type appears in the add-node palette (⌘P),
 labelled with the package it came from.
 
 ## Write the node