no-em-dash pre-commit hook for user-facing strings, existing em-dashes rewritten

frontend/scripts/no-em-dash.ts walks src/ with the TypeScript parser and flags
an em-dash in JSX text, string literals and template text. A bare "—"
placeholder passes, separators go in no-em-dash.allow.json. The script is
identical to index's copy.

frontend/src/components/UserSettings/RemoteAccess.tsx

@@ -159,7 +159,7 @@ export function RemoteAccess() {
       <CardHeader>
         <CardTitle>Remote access</CardTitle>
         <CardDescription>
-          Reach this instance from fluksio.com. Entirely optional — without it,
+          Reach this instance from fluksio.com. Entirely optional. Without it,
           this instance talks to nothing outside your network.
         </CardDescription>
       </CardHeader>
@@ -179,7 +179,7 @@ export function RemoteAccess() {
                       </span>
                     </>
                   ) : status.last_error ? (
-                    `Reconnecting — ${status.last_error}`
+                    `Reconnecting: ${status.last_error}`
                   ) : (
                     "Reconnecting…"
                   )}