Fix viewer share links to use LAN IP; bind Flask to 0.0.0.0

Share links copied from the Share modal were built with
window.location.origin, producing 127.0.0.1 URLs that remote
viewers could never reach.

- Bind Flask to 0.0.0.0 in gdpr_scanner.py (--host default),
  m365_launcher.py, and build_gdpr.py so the server is reachable
  on the local network. Internal loopback URLs (urllib exports,
  webview window, port probe) intentionally keep 127.0.0.1.
- Add /api/local_ip endpoint: UDP probe to 8.8.8.8 discovers the
  active LAN IP without sending real traffic.
- Add _getShareBaseUrl() in viewer.js: fetches /api/local_ip and
  substitutes the LAN IP; falls back to window.location.origin.
- createShareLink and copyTokenLink are now async and await
  _getShareBaseUrl() before building the viewer URL.
- Update CLAUDE.md and static/js/CLAUDE.md with the new invariants.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

static/js/CLAUDE.md

@@ -26,3 +26,4 @@ Never revert to `!!window._googleConnected` / `_fileSources.length > 0` — thos
 
 - **Profile editor accounts** — default to unchecked. Only explicitly saved `user_ids` are checked.
 - **Date presets** — stored as `years * 365` (integer days). Do not use `* 365.25`.
+- **`copyTokenLink` is async** — called from `onclick` attributes as a fire-and-forget (the Promise is unhandled, which is fine). It `await`s `_getShareBaseUrl()` to get the machine's LAN IP before building the URL. Do not make it synchronous or revert to `window.location.origin` directly.