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/functions/backend/db/bots/media-to-attachment.ts

@@ -0,0 +1,23 @@
+import type { BUN_SQLITE_COBBLE_MEDIA } from "@/db/types/db";
+import grabMediaURL from "@/src/functions/backend/media/grab-media-url";
+import type { BotMessageAttachment, MediaType } from "@/src/types";
+
+type Params = {
+    media: BUN_SQLITE_COBBLE_MEDIA;
+};
+
+/**
+ * A `media` row as a chat attachment: its original name (`title`), type
+ * and the private URLs it's served at.
+ */
+export default function mediaToAttachment({ media }: Params): BotMessageAttachment {
+    const { media_url, media_thumbnail_url } = grabMediaURL({ media: { ...media } });
+
+    return {
+        id: Number(media.id),
+        name: media.title || `File ${media.id}`,
+        media_type: (media.media_type || "document") as MediaType,
+        url: media_url || "",
+        thumbnail_url: media_thumbnail_url,
+    };
+}