feat(hub): replace reCAPTCHA with a self-hosted proof of work

Sign-up and passphrase reset sent every visitor's address and browser
details to Google, which needed a consent the sign-up form could not ask
for freely. The hub now issues its own challenge (ALTCHA's scheme, signed
with a key derived from the hub's private key, single-use, 30 minutes)
and the page solves it with SubtleCrypto while the form is filled in.

- GET /v1/users/captcha issues a challenge; 404 captcha_disabled when off.
- [captcha] enabled / max_number replace site_key / secret_key, which are
  now ignored with a warning; MESHBAY_CAPTCHA_ENABLED replaces the old
  variables.
- No Google origin left in the CSP of the hub, the desktop shell or the
  Android shell; captcha_site_key leaves /v1/hub/info.

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

1 files changed, 1 insertions, 2 deletions

diff --git a/packages/meshbay-hub/src/meshbay_hub/static/locales/it.js b/packages/meshbay-hub/src/meshbay_hub/static/locales/it.js
index 0751692..1dd3f52 100644
--- a/packages/meshbay-hub/src/meshbay_hub/static/locales/it.js
+++ b/packages/meshbay-hub/src/meshbay_hub/static/locales/it.js
@@ -138,8 +138,7 @@ export default {
     + 'legame tra loro funziona bene.',
   'register.strength': 'Robustezza: circa {bits} bit. Protegge la copia delle sue '
     + 'chiavi conservata sui node a cui aderisce, quindi vale la pena sceglierla con cura.',
-  'captcha.required': 'Completa il captcha.',
-  'captcha.failed': 'Verifica captcha fallita — riprova.',
+  'captcha.failed': "La verifica anti-robot non è riuscita. Riprovi.",
 
   // Home
   'home.welcome': 'Benvenuto in MeshBay',