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/harness/tools/graphics/graphic-tool-context.ts

@@ -0,0 +1,16 @@
+/**
+ * What the graphic tools of one run work with: the bot, the user it works
+ * for and the place, and a callback that puts a graphic on its message.
+ */
+export type GraphicToolContext = {
+    bot_id: number | string;
+    user_id: number | string;
+    session_id?: number | string | null;
+    workspace_id?: number | string | null;
+    job_id?: number | string | null;
+    /**
+     * Called with a graphic's ref when the run makes or changes it, so its
+     * message always shows it.
+     */
+    onGraphic?: (params: { ref: string }) => void;
+};