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/schemas.ts

@@ -680,7 +680,7 @@ export const HookEventSchema = z.object({
 /**
  * Body of POST /api/approvals/:id/answer (Approvals Inbox).
  * `option` digits are additionally validated against the item's PARSED options
- * in the route — the schema alone must not authorize blind digit-poking.
+ * in the route; the schema alone must not authorize blind digit-poking.
  */
 export const ApprovalAnswerSchema = z
   .object({
@@ -791,9 +791,10 @@ export const SettingsUpdateSchema = z
      */
     agentSkillEnabled: z.boolean().optional(),
     /**
-     * Approvals Inbox UI (header badge + drawer, phone overview answer buttons).
-     * SYNCED, default ON: the surfaces only appear while a prompt is pending.
-     * The server-side store runs regardless (push actions keep working).
+     * Approvals Inbox UI (header bell + drawer, phone overview answer buttons).
+     * SYNCED, default OFF (opt-in): even with items pending, no surface renders
+     * until this is enabled. The server-side store and answer endpoints run
+     * regardless, so push Approve/Deny actions keep working either way.
      */
     approvalsInboxEnabled: z.boolean().optional(),
     tunnelEnabled: z.boolean().optional(),