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>

sdks/node/src/cli.ts

@@ -41,7 +41,7 @@ function printUsage(): void {
   console.log(`Elydora CLI — Tamper-evident audit for AI coding agents
 
 Usage:
-  elydora install   --agent <name> --org_id <id> --agent_id <id> --private_key <key> --kid <kid> [--token <jwt>] [--base_url <url>]
+  elydora install   --agent <name> --org_id <id> --agent_id <id> --private_key <key> --kid <kid> [--token <token>] [--base_url <url>]
   elydora uninstall --agent <name> [--agent_id <id>]
   elydora status
   elydora agents