feat(notification): implement the notification delivery platform

Maps the 31-module plan onto the registry's 19 leaves as packages; the two
edges the registry forbids (provider->httpclient, inbox->messaging) are
replaced by application-owned ports. See docs/notification/module-mapping.md.

Acceptance is not delivery: ProviderSubmissionResult refuses to carry a
delivery outcome, and AMBIGUOUS is a first-class terminal state that blocks
automatic retry and fallback until reconciliation resolves it.

Providers: SES (SigV4 + SNS callback), Twilio (X-Twilio-Signature +
reconciliation), FCM (FID-primary batch), APNs, Web Push (RFC 8030/8291/8292),
SMTP and webhook. Contact points are AES-256-GCM encrypted with a separate
HMAC lookup fingerprint; nothing raw reaches a log, metric tag or exception.

Dispatch commits the attempt row, calls the provider with no transaction open,
then records the outcome; the durable queue uses FOR UPDATE SKIP LOCKED.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

.github/scripts/verify-gradle-wrapper.sh

@@ -26,6 +26,7 @@ readonly EXPECTED_WORKFLOW_LOCK=(
   'ad84000efc438ee7439517b8f85819e62b13dab0aa4f94066c2905060f3bb581  .github/workflows/httpclient-release.yml'
   '59cb3a0ffc687a15eefe96bc5e3a70d42be78e1cc85d2e7f7880dac6124ca4c7  .github/workflows/jpa-r2-evidence.yml'
   '5be7e931db749029d89787da042d6d7cf8e683d60698bd8a2993c29db26355fb  .github/workflows/link-check.yml'
+  '3d5afcef6bf1c65dcd8cad3d1687f07c2cfbb15d360f41251e46f9eb8950baac  .github/workflows/notification-platform.yml'
   '64245586cd5936f1a5647b57f2cd9acd316f96fd75f713b1890decb812e7d5fe  .github/workflows/object-storage-qualification.yml'
   'cbc104ea486c746229895e804e3be7716e056a02cce0588c537bce9f442f8b38  .github/workflows/redis-sdk-topology.yml'
 )