treefmt: apply prettier

Pure `nix fmt` output from the commit before this one — no hand edits.
203 files: 52 md, 42 tsx, 32 js, 32 css, 21 ts, 13 html, 8 json, 3 mjs.

Reproduce with `nix develop -c nix fmt` on the parent commit; the result
should be byte-identical to this tree.

None of the 13 `.prettierignore` entries appears here — verified by
intersecting the changed-file list against the ignore file, with a
control proving the intersection finds a match when one exists.

docs/web-ui/design-guide.md

@@ -2,7 +2,7 @@
 
 Scope: **swarm-ui only** (the swarm-level Preact app — not the per-hive
 dashboard, which has its own older visual language). This doc is the
-*why*: the principles behind how swarm-ui looks and behaves, and the
+_why_: the principles behind how swarm-ui looks and behaves, and the
 concrete rules that follow from them. It deliberately doesn't show what
 things look like — that's `ComponentsPage` (`/components`), the living,
 always-current demo of every primitive in `src/ui/`. Code can't go stale
@@ -21,14 +21,14 @@ repeated here.
   distinction, not decoration for its own sake.
 - **Whimsy** — small, delightful touches are welcome (the per-hive
   dashboard's home-page matrix-rain background, `packages/dashboard/src/
-  home.js`, is the reference example — currently in the dashboard
+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). 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
+  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.
@@ -62,7 +62,7 @@ smooth them instead.
 
 The mechanical contract (base16 slots, semantic vars, what a page's CSS
 is and isn't allowed to reference) lives in `docs/web-ui/css-vars.md` —
-read that for the how. This section is the *policy* layered on top:
+read that for the how. This section is the _policy_ layered on top:
 
 - **User-theming compatible by construction.** The whole point of the
   base16/`colors.css` swap contract is that a user's own theme (stylix
@@ -132,7 +132,7 @@ just bare column headers floating over nothing.
   touch target (`2.75em` ≈ 44px, WCAG 2.5.5) by default, so this isn't
   something each page has to remember.
 - **Phone is a second-class citizen, not an unsupported one.** Things
-  must not *break* at phone width, but don't over-invest in phone
+  must not _break_ at phone width, but don't over-invest in phone
   optimization beyond that. swarm-ui is installable as a PWA, so a
   phone can check status or do basic interactions.
 - **A narrow viewport isn't only a phone** — a tiling-window-manager