style(web): fix prettier config, format entire web/ tree

.prettierrc.json was missing "semi": false, so prettier wanted to add
semicolons to a codebase written without them (763 semicolon-free
statements vs. 150 with, in hand-written .ts; zero hand-written .svelte
files use them at all). That's why prettier --check failed on 249 files
— not because the code was unformatted, but because the config didn't
match the actual house style. Added "semi": false; left printWidth/etc
as configured (printWidth barely moves the failure count: 218/213/212
files at 100/120/140).

Ran `prettier --write .` with the corrected config. Verified
semantics-preserving before and after:
- eslint: 142 problems both before and after, byte-identical
- build passes, 38/38 tests pass
- token-stream diff (whitespace/semicolons/quotes normalized) on all
  218 changed files: only 52 had any remaining token change, all either
  trailing-comma removal (matching trailingComma: "none") or import/
  ternary reflow — no semantic changes
- live smoke test: Knowledge, Tasks, Fleet map, and a chat window
  (AgentTrace, markdown, Scope graph, activity rail) all render
  correctly, no console errors

Most of the diff is shadcn/ui vendor files (lib/components/ui/) moving
from the CLI's own style (double quotes, tabs, semicolons) to house
style; re-running `shadcn-svelte add` on a component will need a
follow-up format pass.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

web/src/lib/hooks/is-mobile.svelte.ts

@@ -1,9 +1,9 @@
-import { MediaQuery } from "svelte/reactivity";
+import { MediaQuery } from 'svelte/reactivity'
 
-const DEFAULT_MOBILE_BREAKPOINT = 768;
+const DEFAULT_MOBILE_BREAKPOINT = 768
 
 export class IsMobile extends MediaQuery {
-	constructor(breakpoint: number = DEFAULT_MOBILE_BREAKPOINT) {
-		super(`max-width: ${breakpoint - 1}px`);
-	}
+  constructor(breakpoint: number = DEFAULT_MOBILE_BREAKPOINT) {
+    super(`max-width: ${breakpoint - 1}px`)
+  }
 }