frontend: trim narrated-history comments in packages/agent, packages/swarm-ui

Continues #3901. Same pattern as tabs.js/swarm.js: cut 'used to be
X, now Y'/'moved to'/'no longer' change-history narration down to
the current design fact, keep every load-bearing rationale intact
(the ResizeObserver feedback-loop note in Header.tsx, the Dropdown-
vs-real-<a> semantics in MetaNav.tsx, etc.).

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

@@ -179,10 +179,7 @@ export function CreateAgentForm() {
             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. 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) */}
+            running commentary on partial implementation. */}
         <Panel title="what this creates" icon="🪪">
           <p>
             Submitting this queues everything a new agent needs: a swarm-level identity, a config