feat: local dev setup with SSR fix and one-command dev script

- Add Next.js instrumentation.ts to polyfill Node.js v25+ broken localStorage
- Add dev-setup.sh for one-command local development setup
- Disable Supabase analytics in config.toml (avoids slow logflare image pull)
- Switch backend dev script to tsx watch for better DX

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

website-monitoring-frontend/supabase/config.toml

@@ -315,7 +315,7 @@ deno_version = 1
 # secret_key = "env(SECRET_VALUE)"
 
 [analytics]
-enabled = true
+enabled = false
 port = 54327
 # Configure one of the supported backends: `postgres`, `bigquery`.
 backend = "postgres"