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/routes/operations.ts

@@ -16,7 +16,7 @@ const operations = new Hono<{ Bindings: Env; Variables: AppVariables }>();
 // POST /v1/operations — Submit a signed EOR
 // ---------------------------------------------------------------------------
 // Operation submission uses the EOR's embedded signature for authentication
-// rather than a Bearer JWT. The agent authenticates via its Ed25519 signature.
+// rather than a Bearer token. The agent authenticates via its Ed25519 signature.
 // We still apply auth middleware to get the org context.
 operations.post(
   '/',