Let bots set a picture from a file they can see

A coordinator asked to set an uploaded logo as a workspace picture could
not: the picture tools take a media id, and nothing ever gave the bot one.
Attachments reached the model as "[Attached image \"logo.png\"]", every
file tool answers with a [file:ID] ref, and an SVG is deliberately stored
as a document rather than an image.

- copyMediaAsPicture copies an approved image into a new picture row
  (bot-image/workspace-image). The source keeps its row and bytes, so a
  message that attached it still loads and changing a picture can never
  take a file away from a conversation.
- grabPictureSource resolves a picture by [file:ID] (the same scope gate
  every file tool uses) or by the user's own upload; parseFileRef reads
  the [file:12] form.
- The new set_picture tool ships on every run: a bot sets its own face,
  the coordinator can also dress a worker. update_workspace gained
  picture_file_id, and setBotPicture/setProfileImage share the copy and
  the delete.
- removeReplacedPicture deletes a replaced picture only when it really is
  one, never a chat upload.
- uploadAndRecordMedia writes images in their own format: PNG stays PNG
  with its transparency, WebP stays WebP, GIF becomes PNG, everything
  else JPEG, and the row records the real mime type (it used to say jpeg
  for every image).
- Pictures change live: BotUpdatedData carries image_media_id and a new
  server:workspace-updated pushes workspace pictures, relayed between
  processes.
- Attachments are labelled with their media id, and BotFilesNote tells a
  bot that a [file:ID] can become a picture.
- grabRunScopes is now the single source of a run's reachable folders,
  shared by the file tools, imports and the picture tools.

src/data/harness-prompts.ts

@@ -49,7 +49,8 @@ You have a folder of your own, kept with the app (not on a computer), and it sta
 
 - list_files shows what's in it; read_file opens one (by its [file:ID] ref or path); write_file saves a text file, make_pdf a PDF, generate_image an image. Move and delete with move_file and delete_file when something is out of date, so the folder stays useful.
 - Text files are chunked and searchable as soon as they're saved. search_files finds the passages that answer a question, by meaning when an embedding model is set and by words otherwise. Search your files before saying you don't know something they may hold, and when the user asks about a document they gave you.
-- Uploaded files land in the same folder, so what the user sent you earlier is searchable later too.
+- Uploaded files land in the same folder, under uploads/ (uploads/2026-10/logo.png), so what the user sent you earlier is searchable later too.
+- A picture can be set from a file: set_picture makes a file your own avatar, and update_workspace sets a workspace's. Both take the [file:ID] ref, so a logo the user sent you is usually ready to go: list_files for it, then set it. An SVG or another kind of file is turned into a PNG first. Its picture is free to change and never removes your file.
 - A file and a folder are two different refs, and you never guess which one from the name:
     - A file you saved is a [file:ID] ref (from write_file, list_files, search_files or import_file). The user sees a chip that opens the file.
     - A folder is a folder ref, e.g. ${folderRef({ volume: "bot", owner_id: 5, path: "reports" })}: the user sees a chip that opens that folder in Files, and nothing is downloaded. Use the volume of the folder you mean ("bot" for your own, "workspace" for a workspace's shared one).