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.tsx

@@ -0,0 +1,16 @@
+import type { BotMessageWithAttachments } from "@/src/types";
+import MessageAttachments from "./message-attachments";
+import UserBubble from "./user-bubble";
+
+/**
+ * One user message: its files, then its text (a file-only message has no
+ * bubble).
+ */
+export default function UserMessage({ text, attachments }: BotMessageWithAttachments) {
+    return (
+        <>
+            <MessageAttachments attachments={attachments} />
+            {text ? <UserBubble text={text} /> : null}
+        </>
+    );
+}