* Open SSH host add/edit form in modal dialog
Form moves from inline to a viewport-stable modal (STA-3067) so fields stay
accessible with long host lists. Includes sticky header/footer, dirty-state
protection against outside click, and session-aware Advanced state reset on
cancel/reopen.
* fix: add missing SshTargetForm localization keys
Sync en.json catalog for modal title/description strings so
verify:localization-catalog passes in static analysis.
* fix: translate SshTargetForm modal strings in es/ja/ko/zh
Add non-English catalog entries for the new modal title and
description keys so localized UIs match English.
* Prevent SSH form double-submit and fix dismissal detection
Adds a saving state to prevent concurrent saves when a user double-clicks
the submit button. Fixes outside-click dismissal by correctly tracking form
state across re-renders using refs. Extracts session termination logic to
a reusable module.
* fix: stop mutating formRef during render in SshTargetForm
React Doctor fails the static-analysis gate when refs are written during
render. Sync form into formRef in an effect so render stays pure.
