Add the harness, envs, per-bot models and chat attachments

- Harness: providers, model catalog synced hourly, automatic free picks,
  cooldowns, tool loop with context trimming, MCP computer tools
- Bots queue runs replies and tasks through the harness; jobs wait
  (attempt refunded) while every model is resting
- Envs: Settings > Environment, scoped general/workspace/computer,
  written to computers and redacted from tool output
- Models: Settings > Models, per-harness provider select defaulting to
  OpenRouter, and a models modal on each bot's chat (the coordinator's
  edits the defaults)
- Chat: thinking row while a reply runs, file attachments (upload,
  paste, drop) that replies read as images, audio and document text
- Fix media uploads failing after a user's first file, and private
  files being served from the public media path

Co-Authored-By: Claude Opus 5.5 <[email protected]>

src/pages/admin/bots/[bot_id]/(partials)/user-message-group.tsx

@@ -1,16 +1,17 @@
 import Stack from "@moduletrace/twui/layout/Stack";
 import type { MessageGroup } from "../(utils)/group-messages";
-import UserBubble from "./user-bubble";
+import UserMessage from "./user-message";
 import GroupTimestamp from "./group-timestamp";
 
 /**
- * Right-aligned ink bubbles, one timestamp under the group.
+ * Right-aligned ink bubbles (each message's files above it), one
+ * timestamp under the group.
  */
 export default function UserMessageGroup({ group }: { group: MessageGroup }) {
     return (
         <Stack className="w-full gap-1! items-end">
             {group.messages.map((message) => (
-                <UserBubble key={message.id} text={message.text || ""} />
+                <UserMessage key={message.id} {...message} />
             ))}
             <GroupTimestamp at={group.at} />
         </Stack>