feat(screenshots): real netOrk screenshots from an anonymized demo copy

The site has shown hand-built JSX mockups of the UI so far. This adds the
tooling to replace them with screenshots of the real application:

- scripts/demo/up.sh restores a pg_dump of a production database into a
  local Postgres and starts netOrk (a pinned release, default v0.28.0) with
  only the API and the UI: no worker, no beat, no Redis, a random encryption
  key. Nothing polls and nothing can reach a device.
- scripts/demo/anonymize.py rewrites every text, JSON and address column of
  every table: domains to example.demo, private IPv4 per /16 with the host
  part kept, public addresses into the documentation ranges, MACs with the
  vendor prefix kept, e-mail addresses and configured names. Secrets are
  emptied by column name, one admin "netork" is left. It refuses non-local
  databases and ends with a leak report. The real-to-demo name map lives
  outside the repo.
- scripts/screenshots/capture.py drives headless Chromium through a
  declarative list of pages, logs in to the demo copy by itself, and aborts
  every non-GET API request, so taking screenshots cannot change anything.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

.gitignore

@@ -8,3 +8,7 @@ memory/
 
 # Deploy target + registry token
 deploy.env
+
+# Screenshot tooling: bytecode, and database dumps that hold production data
+__pycache__/
+*.dump