nessa: retire the API copy now served by nessa-api.freno.me

The Nessa API (nessaDb.*, nessa.community.*, Clerk auth and the Clerk user
webhook) lives in the Nessa repo's server/ on pan. This copy never served
the app: RemoteAPIClient wraps every input in {"input": …}, which the stock
tRPC adapter here reads as the input itself (queries 404, writes no-op).
Clerk's webhook already targets nessa-api.freno.me.

Drops the routers, nessa-auth, the webhook, NessaConnectionFactory, the
NESSA_* env and the now-unused @clerk/backend and svix. Nessa's marketing,
privacy and deletion pages stay.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

.env.example

@@ -55,15 +55,8 @@ TURSO_DB_TOKEN="<rotate-in-turso-dashboard>"                        # eyJ...
 TURSO_DB_API_TOKEN="<rotate-in-turso-dashboard>"                   # org-level API token
 TURSO_LINEAGE_URL="libsql://<lineage-db>.turso.io"
 TURSO_LINEAGE_TOKEN="<rotate-in-turso-dashboard>"
-NESSA_DB_URL="libsql://<nessa-db>.turso.io"
-NESSA_DB_TOKEN="<rotate-in-turso-dashboard>"
-# Clerk authentication — rotate via Clerk Dashboard or `clerk api .../rotate_secret_keys`
-NESSA_CLERK_SECRET="sk_test/live_<rotate-in-clerk-dashboard>"   # secret key (sk_test_... for dev, sk_live_... for prod)
-NESSA_CLERK_JWT_ISSUER="https://<your-app>.clerk.accounts.dev"  # JWT issuer from Clerk Dashboard
-NESSA_CLERK_WEBHOOK_SECRET="whsec_<rotate-in-clerk-dashboard>"  # Svix signing secret from Clerk Dashboard → Webhooks → Signing Secret
 
 APPLE_CLIENT_ID_LINEAGE=com...
-APPLE_CLIENT_ID_NESSA=com...
 
 # ── Infra / integration tokens ──
 INFILL_BEARER_TOKEN="<rotate-at-infill-service>"