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/desktop-patterns.ts

@@ -7,7 +7,8 @@
 // color (see background.svelte.ts) sits underneath as `background-color`,
 // showing through the transparent gaps when the user wants one.
 
-export type BackgroundPatternId = 'none' | 'dots' | 'bubbles' | 'grid' | 'stripes' | 'checks' | 'zigzag' | 'rings'
+export type BackgroundPatternId =
+  'none' | 'dots' | 'bubbles' | 'grid' | 'stripes' | 'checks' | 'zigzag' | 'rings'
 
 export interface PatternDef {
   id: BackgroundPatternId
@@ -47,7 +48,8 @@ export const PATTERNS: PatternDef[] = [
   {
     id: 'stripes',
     label: 'Stripes',
-    css: (c, s) => `background-image: repeating-linear-gradient(45deg, ${c} 0 ${px(2, s)}, transparent ${px(2, s)} ${px(14, s)});`
+    css: (c, s) =>
+      `background-image: repeating-linear-gradient(45deg, ${c} 0 ${px(2, s)}, transparent ${px(2, s)} ${px(14, s)});`
   },
   {
     id: 'checks',