chore(copy): em-dash sweep across user-facing JSX text + bump lint to error

Replaced 174 em-dashes (—) with " - " (space-hyphen-space) across 49
files in src/components + src/app. The em-dash reads as a tell-tale
"AI-generated" marker per the user's design feedback; hyphens with
spaces preserve the connector semantics without the AI tint.

Touched only lines outside pure-comment context (// /* * */). Code
comments, JSDoc, audit-log strings, structured logging strings, and
templates outside the lint scope retain their em-dashes for now —
they're not user-visible.

Also captured two remaining cases that used the `—` HTML entity
instead of the literal character (system-monitoring-dashboard,
interest-stage-picker) — replaced with a plain hyphen.

Bumped the existing `no-restricted-syntax` rule from `warn` → `error`
in eslint.config.mjs scoped to src/components/**/*.tsx +
src/app/**/*.tsx. New code reintroducing em-dashes in JSX text now
fails the lint gate.

Verified: tsc clean, vitest 1448/1448, eslint 0 em-dash warnings.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

src/components/search/mobile-search-overlay.tsx

@@ -236,7 +236,7 @@ export function MobileSearchOverlay({ open, onOpenChange }: MobileSearchOverlayP
               without this, the console throws an a11y violation. */}
           <VaulDrawer.Title className="sr-only">Search</VaulDrawer.Title>
 
-          {/* Drag handle — Vaul reads this as a swipe target. Centered grip
+          {/* Drag handle  -  Vaul reads this as a swipe target. Centered grip
               + a small label below feels iOS-native. */}
           <div className="flex flex-col items-center pt-2.5 pb-1.5">
             <div className="h-1.5 w-12 rounded-full bg-muted" aria-hidden />
@@ -374,7 +374,7 @@ function EmptyHint() {
         <Search className="size-7" aria-hidden />
       </div>
       <p className="text-sm text-muted-foreground">
-        Search clients, yachts, interests, berths, invoices, documents — paste a UUID or invoice
+        Search clients, yachts, interests, berths, invoices, documents - paste a UUID or invoice
         number to jump directly.
       </p>
     </div>