Panel 2.8.0 removed the server-side happ-encrypt endpoint, so for users
without a stored crypto link the backend leaves {{HAPP_CRYPT4_LINK}}
unresolved and the subscriptionLink button silently disappeared
(isValidDeepLink requires '://').
- BlockButtons: resolve button templates client-side at render (with username,
like the panel's own subpage) instead of dropping the button; collapse
double-prefixed happ://crypt4/happ://cryptN/... resolvedUrl from old backends
- templateEngine: collapse a hardcoded happ://cryptN/ prefix before
{{HAPP_CRYPT[34]_LINK}}; cache crypt-link generation (jsencrypt RSA-4096 is
slow on weak devices and re-randomizes every call)
- Connection: in happ_cryptolink mode force the crypt link only when the button
fell back to the plain subscription link or kept unresolved templates - an
explicit Subpage link (e.g. happ://add/...) now wins, so Subpage edits apply