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/pages/Signals.svelte

@@ -71,24 +71,51 @@
     return severityFilter === 'all' ? list : list.filter((s) => s.severity === severityFilter)
   }
 
-  const open = $derived(bySeverity(signals.filter((s) => ['raised', 'acknowledged', 'acting'].includes(s.state))))
+  const open = $derived(
+    bySeverity(signals.filter((s) => ['raised', 'acknowledged', 'acting'].includes(s.state)))
+  )
   const muted = $derived(bySeverity(signals.filter((s) => s.state === 'muted')))
-  const resolved = $derived(bySeverity(signals.filter((s) => ['resolved', 'failed'].includes(s.state))))
+  const resolved = $derived(
+    bySeverity(signals.filter((s) => ['resolved', 'failed'].includes(s.state)))
+  )
 
   function makeColumns(showActions: boolean, actingVal: string | null): DataTableColumn<Signal>[] {
     const base: DataTableColumn<Signal>[] = [
-      { key: 'target', header: 'Target', class: 'font-mono text-xs', width: '180px', accessor: (s) => s.target ?? '—', truncate: true },
+      {
+        key: 'target',
+        header: 'Target',
+        class: 'font-mono text-xs',
+        width: '180px',
+        accessor: (s) => s.target ?? '—',
+        truncate: true
+      },
       { key: 'kind', header: 'Kind', width: '120px' },
-      { key: 'severity', header: 'Severity', render: 'status-badge', renderProps: { kind: 'severity' }, width: '100px' },
-      { key: 'state', header: 'State', render: 'status-badge', renderProps: { kind: 'state' }, width: '110px' },
+      {
+        key: 'severity',
+        header: 'Severity',
+        render: 'status-badge',
+        renderProps: { kind: 'severity' },
+        width: '100px'
+      },
+      {
+        key: 'state',
+        header: 'State',
+        render: 'status-badge',
+        renderProps: { kind: 'state' },
+        width: '110px'
+      },
       { key: 'occurrence_count', header: 'Occurrences', width: '100px', align: 'right' },
-      { key: 'last_seen_at', header: 'Last seen', render: 'date', width: '170px' },
+      { key: 'last_seen_at', header: 'Last seen', render: 'date', width: '170px' }
     ]
     if (showActions) {
       base.push({
-        key: '_actions', header: '', render: SignalActions,
+        key: '_actions',
+        header: '',
+        render: SignalActions,
         renderProps: { acting: actingVal, onAck: ack, onMute: mute, onResolve: resolve },
-        align: 'right', headerClass: 'text-right', width: '220px'
+        align: 'right',
+        headerClass: 'text-right',
+        width: '220px'
       })
     }
     return base