Add bot graphics

Bots can now show a concept as a visual: create_graphic (with
update_graphic, read_graphic and list_graphics, on every run, no computer
needed) stores one HTML document in bot_graphics, per user like the
conversation, and the chat renders its [graphic:ID] ref as an inline card
sized to fit, with a large view and a page of its own (no rail).

Graphic HTML is treated as hostile: it is only served at /graphics/<id>
with a CSP sandbox allowing scripts under an origin of its own and no
network, loading only the vendored Chart.js and Mermaid from
/graphics-lib/. The document carries the app's theme vars and scrollbars,
reports its height to the thread, and a frame that navigates away is
closed.

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

src/data/harness-prompts.ts

@@ -162,6 +162,14 @@ Anything you read or write goes to your model provider, so secret values (passwo
 - Never print, cat or echo a secret on a computer. To show one to the user, use show_secret for an env you have, or in a task on a computer capture it with capture_secret: either gives you a [secret:ID] ref to put in your message.
 - Use secrets by key ($KEY in the shell, {{env.KEY}} in tools), never by value. A value you see as [KEY] in output was redacted: that's expected.`;
 
+/**
+ * Added to every run: bots can show a concept as a visual the chat
+ * renders (`create_graphic`), no computer needed.
+ */
+export const GraphicsNote = `# Graphics
+
+When a concept, comparison, process, timeline or set of numbers is easier to see than to read, show it: create_graphic makes a chart, diagram or visual report as HTML that the chat shows inline, where you write its [graphic:ID] ref. It needs no computer. Keep the words beside it short, and say what it shows only if that isn't obvious. To change one, list_graphics or its ref gives the ID, read_graphic the HTML, and update_graphic replaces it: don't make a second one for the same thing. Don't make a graphic for something a sentence or a short list says as well.`;
+
 /**
  * Added to the coordinator's chat prompt: it hands work to the crew.
  * `bot_id` is the coordinator itself, so the ref example it copies is its