feat(uat-batch-15): supplemental-info link reusable until expiry

The supplemental-info token now stays valid for re-submissions until
the 14-day TTL expires. Previously the link was single-use:
`applySubmission` required `consumedAt IS NULL`, which locked clients
out of correcting a typo or finishing a partial submission.

- Service: drops the `isNull(consumedAt)` filter; TTL is the sole
  validity check. `consumedAt` is still stamped on each submit so the
  rep / loader can see "last submitted at" context.
- Public form: the "already submitted" lockout screen is removed.
  Instead, when the token has been used before, the form renders with
  the prefill (already reflecting the latest data) plus a soft amber
  banner noting that changes overwrite the previous submission.
- Drive-by em-dash fix on the post-submit thank-you copy (matches the
  Wave-1 lint guard).

tsc clean. 1419/1419 vitest pass.

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

src/lib/services/supplemental-forms.service.ts

@@ -8,7 +8,7 @@
  *      updates, consume token. All inside one transaction.
  */
 
-import { and, eq, isNull } from 'drizzle-orm';
+import { and, eq } from 'drizzle-orm';
 import crypto from 'node:crypto';
 
 import { db } from '@/lib/db';
@@ -193,14 +193,16 @@ export async function applySubmission(token: string, input: SubmissionInput): Pr
   }
 
   await db.transaction(async (tx) => {
+    // Reusable-until-expiry: the link stays valid for repeat
+    // submissions until it expires. `consumedAt` is still stamped on
+    // first submit so the rep / loader can show "last submitted at
+    // <time>" context, but it no longer gates the submission. The TTL
+    // gate below is the sole validity check.
     const row = await tx.query.supplementalFormTokens.findFirst({
-      where: and(
-        eq(supplementalFormTokens.token, token),
-        isNull(supplementalFormTokens.consumedAt),
-      ),
+      where: eq(supplementalFormTokens.token, token),
     });
     if (!row) {
-      throw new ConflictError('This link has already been used or is no longer valid.');
+      throw new ConflictError('This link is no longer valid.');
     }
     if (row.expiresAt.getTime() < Date.now()) {
       throw new ConflictError('This link has expired.');