Complete Better Auth migration, harden security, update all docs

Console:
- Rewrite auth from JWT decoding to Better Auth useSession()
- Add auth-client.ts with createAuthClient
- Remove elydora_token localStorage, dead auth API functions
- Fix login/register pages to use signIn.email/signUp.email

Server:
- Upgrade better-auth ^1.2.0 → ^1.5.5
- CORS: enforce allowlist on all environments
- Sync auth service and middleware with backend

SDKs:
- Deprecate login/register in Node, Python, Go SDKs
- Update READMEs to show direct token initialization

Config:
- Sanitize .env with dev-only placeholder values
- Update helm chart and install scripts

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

packages/server/src/shared/index.ts

@@ -60,5 +60,5 @@ export {
   DEFAULT_EPOCH_INTERVAL_MS,
   MAX_QUERY_LIMIT,
   DEFAULT_QUERY_LIMIT,
-  DEFAULT_JWT_TTL_SECONDS,
+  DEFAULT_SESSION_TTL_SECONDS,
 } from './constants/index.js';