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)/composer-attachments.tsx

@@ -0,0 +1,30 @@
+import Row from "@moduletrace/twui/layout/Row";
+import type { PendingAttachment } from "../(hooks)/use-composer-attachments";
+import ComposerAttachmentChip from "./composer-attachment-chip";
+
+type Props = {
+    pending: PendingAttachment[];
+    onRemove: (params: { key: string }) => void;
+};
+
+/**
+ * The next message's files, just above the composer rule.
+ */
+export default function ComposerAttachments({ pending, onRemove }: Props) {
+    if (!pending.length) return null;
+
+    return (
+        <Row className="gap-2! px-6 pb-3">
+            {pending.map((item) => (
+                <ComposerAttachmentChip
+                    key={item.key}
+                    name={item.name}
+                    status={item.status}
+                    attachment={item.attachment}
+                    error={item.error}
+                    onRemove={() => onRemove({ key: item.key })}
+                />
+            ))}
+        </Row>
+    );
+}