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/custom-fields/custom-fields-manager.tsx

@@ -171,7 +171,7 @@ export function CustomFieldsManager() {
           the form <code className="rounded bg-amber-100 px-1">{`{{custom.fieldName}}`}</code> now
           expand in EOI/contract/email templates for client/interest/berth contexts. They still
           don&rsquo;t plug into the global search index, the berth recommender, or the entity-diff
-          audit log — use them for rep-only annotations and template-merge values, but anything
+          audit log - use them for rep-only annotations and template-merge values, but anything
           load-bearing for the deal flow still needs a first-class column.
         </span>
       </WarningCallout>