Add PWA service worker (via vite plugin), use dynamic viewport units for interface size (improves mobile experience), replace default vue homepage with basic info

backend/src/database.py

@@ -62,6 +62,11 @@ class Chat(Base):
     last_message_preview: Mapped[Optional[str]]
     last_message_time: Mapped[Optional[int]]
 
+    # Chat Controller defines when to forward messages to agents and users, and what messages each can see
+    # Controllers are: default (all messages to all participants), mention (notify agents by specific mentions), active (llm agent selecting next agent to respond), arena
+    #controller_kind: Mapped[str]
+    #controller_data = mapped_column(JSON, default={})
+
 # Stores membership of agents in chats. If a record exists linking an agent and a chat,
 # it means the agent participates in that chat.
 class Membership(Base):