Feat/code login (#671)

* feat: add chatbox email code login

* feat(auth): new modal style; unify app -> website link with openLinkWithAuth comp.

* feat(auth): add loading state to auth btns/links

* refactor: centralize chatbox redirect origins and support beta website env

- add buildChatboxUrl helper in remote.ts and replace hardcoded redirect_app hosts across renderer entry points\n- update openLinkWithAuth to resolve website URLs from getChatboxOrigin instead of a fixed production origin\n- inject USE_LOCAL_CHATBOX and USE_BETA_CHATBOX into the renderer build so beta/local website switching works in dev\n- keep redirect targets environment-aware for settings, guide, about, error tips, welcome cards, and license flows

* chore: improve translation

* fix: harden code login modal and auth link interactions

- keep the verification-code step stable after the first successful send instead of inferring it from transient UI state\n- lock the email field only while the resend countdown is active, and reset code-step state when the email changes after countdown expiry\n- invalidate in-flight send-code and verify-code requests on modal reset so stale responses cannot mutate state or complete login after close\n- add synchronous ref-based click guards to openLinkWithAuth entry points to prevent duplicate requests before React disabled state is applied\n- update the guide free-plan action and chatbox AI entry points to share the same duplicate-click protection behavior

* feat: remove beta host

* feat(ios): update ios target to 16.0

(cherry picked from commit bc6959b3eaba99cd7b2735a85547ea7d682c9fdc)