swarm-ui: give Panel an optional header icon slot

Adds an `icon` prop to Panel (small emoji glyph left of the title,
aria-hidden, chosen per panel with no default) and wires it into every
current Panel caller: hives (bee), create-agent's form (robot) and info
panel (identity card, moved off the info panel's body copy where it
started as a one-off), jobs (puzzle piece), the components gallery
itself (toolbox), and the 404 page (compass). Adds a components-page
demo section and a whimsy-section pointer in the design guide.

Closes: #3508

docs/web-ui/design-guide.md

@@ -24,7 +24,13 @@ repeated here.
   home.js`, is the reference example — currently in the dashboard
   package, not swarm-ui itself, but the pattern it sets applies here
   too). Whimsy still has to clear the accessibility bar below (motion,
-  in particular).
+  in particular). swarm-ui's own reference example: `Panel`'s optional
+  `icon` prop (`src/ui/panel/Panel.tsx`), a small emoji glyph in a
+  panel's header, chosen per panel with no default — grew out of a
+  one-off emoji dropped into a single page's copy, which wasn't whimsy
+  in this sense (a *consistent*, reusable touch) until it became a real
+  prop every panel can opt into. `aria-hidden`, since it's decorative —
+  the title text is still the actual label.
 - **Efficient navigation** — minimize clicks/hops for a common task.
 - **Avoid junk drawers.** A control belongs next to the thing it
   affects, not tucked into a catch-all menu. Concrete anti-example (not

frontend/packages/swarm-ui/src/App.tsx

@@ -10,7 +10,7 @@ import { Panel } from './ui/panel/Panel.js';
 
 function NotFound() {
   return (
-    <Panel title="404">
+    <Panel title="404" icon="🧭">
       <p>no route here.</p>
     </Panel>
   );

frontend/packages/swarm-ui/src/pages/ComponentsPage.tsx

@@ -88,7 +88,7 @@ function RefreshIntervalPickerSample() {
 
 export function ComponentsPage() {
   return (
-    <Panel title="components">
+    <Panel title="components" icon="🧰">
       <p class="components-intro">
         Every primitive in <code>src/ui/</code>, shown in each mode it supports. Sample data
         only — nothing here calls the API.
@@ -101,6 +101,11 @@ export function ComponentsPage() {
         <Sample label="without title">
           <Panel>panel body content, no title</Panel>
         </Sample>
+        <Sample label="with icon (per panel, no default — see the doc comment)">
+          <Panel title="example title" icon="✨">
+            panel body content
+          </Panel>
+        </Sample>
         <Sample label="with actions (e.g. HivesPage's refresh picker)">
           <Panel
             title="example title"

frontend/packages/swarm-ui/src/pages/CreateAgentPage.css

@@ -36,10 +36,6 @@
   flex: 1 1 0;
   min-width: 16em;
 }
-.create-agent-info-glyph {
-  margin: 0 0 0.5em;
-  font-size: 2em;
-}
 .create-agent-intro {
   margin: 0 0 1.5em;
   color: var(--muted);

frontend/packages/swarm-ui/src/pages/CreateAgentPage.tsx

@@ -127,7 +127,7 @@ export function CreateAgentPage() {
   return (
     <div class="create-agent-layout">
       <div class="create-agent-form-col">
-        <Panel title="create agent">
+        <Panel title="create agent" icon="🤖">
           <p class="create-agent-intro">
             Create a new agent's swarm-level identity. This only queues the job — check{' '}
             <Link href="/jobs">jobs</Link> to watch it settle.
@@ -180,11 +180,11 @@ export function CreateAgentPage() {
             literal behaviour (deploying the container onto the hive isn't
             wired up server-side yet — see this file's top comment) —
             mara's explicit call on this copy: read as finished, not as a
-            running commentary on partial implementation. */}
-        <Panel title="what this creates">
-          <p class="create-agent-info-glyph" aria-hidden="true">
-            🪪
-          </p>
+            running commentary on partial implementation. The 🪪 glyph that
+            used to sit here as body copy now lives on `Panel`'s own `icon`
+            prop instead — it's what prompted that prop to exist at all
+            (see Panel.tsx's doc comment) */}
+        <Panel title="what this creates" icon="🪪">
           <p>
             Submitting this queues everything a new agent needs: a swarm-level identity, a config
             repo on the forge with the operator added as a collaborator, and a container running

frontend/packages/swarm-ui/src/pages/HivesPage.tsx

@@ -115,6 +115,7 @@ export function HivesPage() {
   return (
     <Panel
       title="hives"
+      icon="🐝"
       actions={<RefreshIntervalPicker id="hives-refresh" value={intervalMs} onChange={setIntervalMs} />}
     >
       {error ? <ApiErrorPanel context="failed to load the hive roster" problem={error} /> : null}

frontend/packages/swarm-ui/src/pages/JobsPage.tsx

@@ -18,7 +18,7 @@ import './JobsPage.css';
 
 export function JobsPage() {
   return (
-    <Panel title="jobs">
+    <Panel title="jobs" icon="🧩">
       <JobqRollup endpoint="/api/jobq/rollup" />
       <JobqGraph endpoint="/api/jobq/graph" />
     </Panel>

frontend/packages/swarm-ui/src/ui/panel/Panel.css

@@ -15,6 +15,10 @@
   font-size: 1em;
   font-weight: 600;
 }
+.ui-panel-icon {
+  font-size: 1.2em;
+  line-height: 1;
+}
 /* `margin-left: auto` (not `justify-content: space-between` on the
    header) so actions still land at the right edge even on the rare
    panel that has actions but no title. */

frontend/packages/swarm-ui/src/ui/panel/Panel.tsx

@@ -11,22 +11,44 @@
 // dedicated row stealing vertical space from the panel's actual
 // content either). `HivesPage`'s refresh-interval picker is the
 // motivating caller.
+//
+// `icon` is a small header glyph, left of the title — the swarm-ui
+// design guide's own whimsy reference (before this, the guide only
+// pointed at the dashboard's matrix-rain background). Grew out of
+// CreateAgentPage's one-off 🪪 dropped straight into a panel's body
+// copy: mara's call on review was that a single ad-hoc emoji isn't
+// whimsy in the guide's sense (small, delightful, *consistent*), it
+// should be a real theme every panel can opt into the same way. Plain
+// `string` (an emoji literal), not an icon-library asset — same
+// lightweight-glyph precedent `RefreshIntervalPicker`'s 🕐 set before
+// this. Chosen per panel, no default: not every panel needs one, and
+// there's no single semantic mapping (e.g. "jobs" pages) worth
+// hardcoding. `aria-hidden` — decorative only, the title text still
+// carries the actual label, so this never becomes a second source of
+// truth an assistive-tech user has to parse.
 import type { ComponentChildren } from 'preact';
 import './Panel.css';
 
 export function Panel({
   title,
+  icon,
   actions,
   children,
 }: {
   title?: string;
+  icon?: string;
   actions?: ComponentChildren;
   children: ComponentChildren;
 }) {
   return (
     <section class="ui-panel">
-      {title || actions ? (
+      {title || icon || actions ? (
         <div class="ui-panel-header">
+          {icon ? (
+            <span class="ui-panel-icon" aria-hidden="true">
+              {icon}
+            </span>
+          ) : null}
           {title ? <h2 class="ui-panel-title">{title}</h2> : null}
           {actions ? <div class="ui-panel-actions">{actions}</div> : null}
         </div>