fix(audit-wave-9): copy/terminology sweep (copy-auditor)

Address the highest-impact items from the copy-auditor's CRITICAL +
HIGH + MEDIUM bands:

**C2 portal raw-status leak**
- Drop the staff-only `leadCategory` chip from the portal interests
  page entirely. Privacy + optics: clients should never see "hot lead"
  in their own portal. `eoiStatus` was already wrapped in
  `portalSigningLabel`; only the categorical chip remained.

**C3 signing-status label drift**
- Add `src/lib/labels/document-status.ts` as the single source of
  truth for the {draft, sent, partially_signed, completed, expired,
  cancelled} lifecycle: labels (CRM + portal variants), StatusPill
  variant, and the "active / in-flight" set.
- Wire it into interest-eoi-tab, interest-contract-tab,
  interest-reservation-tab — they previously redefined identical
  STATUS_LABELS / ACTIVE_STATUSES blocks per-file.

**H1 + M3 verbiage codemod**
- `Save Changes` → `Save changes` (sentence case, matches the
  surrounding admin/CRM pattern).
- `Saving...` (ASCII three dots) → `Saving…` (Unicode ellipsis).
  Matches the project's UTF-8-elsewhere convention and reads
  correctly via screen-readers.

**M1 envelope jargon → signing request**
- smart-archive-dialog: "Leave envelope pending" → "Leave signing
  request pending"; "Void the signing envelope" → "Cancel the signing
  request"; section header updated to match.
- document-detail: "voids the signing envelope" → "cancels the signing
  request".
- bulk-archive-wizard: "leave invoices/signing envelopes alone" →
  "leave invoices/signing requests alone".
- Documenso admin page intentionally keeps `envelope` (dev/integration
  vocabulary).

**M5 Hot Lead casing**
- Normalize `Hot Lead` / `General Interest` / `Specific Qualified` to
  sentence case in `constants.ts` LABEL_OVERRIDES and all per-file
  lead-category maps so the CRM trend (sentence case) is consistent.

**C1 surface-level rename**
- "Linked prospect (optional)" → "Linked interest (optional)" on the
  berth status-change dialog.
- "Deal Documents" tab → "Interest Documents" (URL/route kept as
  `/deal-documents` to avoid breaking deep links; rename deferred).

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

src/components/interests/interest-detail-header.tsx

@@ -54,8 +54,8 @@ function resolveOutcomeBadge(outcome: string | null | undefined) {
 
 const CATEGORY_LABELS: Record<string, string> = {
   general_interest: 'General',
-  specific_qualified: 'Specific Qualified',
-  hot_lead: 'Hot Lead',
+  specific_qualified: 'Specific qualified',
+  hot_lead: 'Hot lead',
 };
 
 interface InterestDetailHeaderProps {