feat(approvals): make the inbox opt-in (default OFF) and drop em-dashes

Owner decision: every Approvals Inbox UI surface (header bell, drawer,
phone overview answer strips, reload seeding) now requires enabling
approvalsInboxEnabled in App Settings -> Panels; only an explicit true
turns it on. The store, endpoints, and push Approve/Deny actions keep
running regardless (the push buttons are already opt-in per subscription).

Also replaces em-dashes with plain punctuation across the newly authored
comments, docs, and strings.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

src/web/public/styles.css

@@ -10643,7 +10643,7 @@ kbd {
   display: none !important;
 }
 
-/* "Approvals" header bell — appears ONLY while prompts are pending (JS toggles
+/* "Approvals" header bell: appears ONLY while prompts are pending (JS toggles
    the marker class on count changes), so it ships hidden and stays out of the
    default header. Same marker pattern as the attachments button. */
 .btn-approvals {
@@ -10672,7 +10672,7 @@ kbd {
   pointer-events: none;
 }
 
-/* Approvals Inbox drawer — same shell as the attachment history drawer. */
+/* Approvals Inbox drawer: same shell as the attachment history drawer. */
 .approvals-drawer {
   position: fixed;
   top: var(--header-height);