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/interface/flow-editor.md

@@ -29,7 +29,7 @@ banner tells you when it is not.
 
 ## Adding a node
 
-**Add node** on the dock, or ⌘K / Ctrl-K for the command palette, which also
+**Add node** on the dock, or ⌘P / Ctrl-P for the command palette, which also
 jumps between flows and offers your shared nodes. Pick a type and it appears on
 the canvas with its panel open.
 
@@ -122,7 +122,7 @@ the edges, then publish.
 
 | Chord | Action |
 |---|---|
-| ⌘K / Ctrl-K | command palette |
+| ⌘P / Ctrl-P | command palette |
 | ⌘S / Ctrl-S | publish the flow — or, with focus in the code editor, apply the code |
 | ⌘Z / ⌘⇧Z | undo / redo (the flow; the code editor has its own) |
 | ⌘C / ⌘V | copy and paste nodes, including between flows |