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/admin/users/user-form.tsx

@@ -221,7 +221,7 @@ function UserFormBody({ open, onOpenChange, user, onSuccess }: UserFormProps) {
                   required
                 />
                 <p className="text-xs text-muted-foreground">
-                  How this user appears across the app — usually their full name, but they can pick
+                  How this user appears across the app - usually their full name, but they can pick
                   a nickname.
                 </p>
               </div>
@@ -238,7 +238,7 @@ function UserFormBody({ open, onOpenChange, user, onSuccess }: UserFormProps) {
                 />
                 {isEdit && email.trim().toLowerCase() !== originalEmail.toLowerCase() ? (
                   <p className="text-xs text-amber-600">
-                    You&apos;ll be asked to confirm — the original address will receive an automated
+                    You&apos;ll be asked to confirm - the original address will receive an automated
                     notice that you, the admin, changed their sign-in email.
                   </p>
                 ) : isEdit ? (