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>

src/server/db-connections.ts

@@ -3,7 +3,6 @@ import { env } from "~/env/server";
 
 let mainDBConnection: Client | null = null;
 let lineageDBConnection: Client | null = null;
-let nessaDBConnection: Client | null = null;
 let nookDBConnection: Client | null = null;
 
 export function ConnectionFactory() {
@@ -28,17 +27,6 @@ export function LineageConnectionFactory() {
   return lineageDBConnection;
 }
 
-export function NessaConnectionFactory() {
-  if (!nessaDBConnection) {
-    const config = {
-      url: env.NESSA_DB_URL,
-      authToken: env.NESSA_DB_TOKEN
-    };
-    nessaDBConnection = createClient(config);
-  }
-  return nessaDBConnection;
-}
-
 export function NookConnectionFactory() {
   if (!nookDBConnection) {
     const config = {