chore(style): codebase em-dash sweep + minor layout polish

Replaces every em-dash and en-dash with regular ASCII hyphens
across comments, JSX strings, and dev-facing logs. Mostly cosmetic
but stops the inconsistent mix that crept in over the last few
months (some files used em-dashes in comments, others didn't,
some used both).

Bundles two small dashboard-layout tweaks that touch a couple of
already-modified files:
- (dashboard)/layout.tsx main padding goes from p-6 to pt-3 px-6
  pb-6 so page content sits closer to the topbar.
- Sidebar now receives the ports list it needs for the footer
  port switcher.

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

src/app/api/v1/admin/duplicates/handlers.ts

@@ -40,7 +40,7 @@ export async function listHandler(_req: Request, ctx: AuthContext): Promise<Next
       .map((p) => {
         const a = clientById.get(p.clientAId);
         const b = clientById.get(p.clientBId);
-        if (!a || !b) return null; // FK orphan — shouldn't happen, but be defensive
+        if (!a || !b) return null; // FK orphan - shouldn't happen, but be defensive
         // Skip pairs where one side has already been merged or archived.
         if (a.mergedIntoClientId || b.mergedIntoClientId) return null;
         return {