WIP: Major cleanup - move Attachment to consumers, simplify agent API

- Removed Attachment from agent package (now in web-ui/coding-agent)
- Agent.prompt now takes (text, images?: ImageContent[])
- Removed transports from web-ui (duplicate of agent package)
- Updated coding-agent to use local message types
- Updated mom package for new agent API

Remaining: Fix AgentInterface.ts to compose UserMessageWithAttachments

packages/web-ui/src/tools/extract-document.ts

@@ -1,4 +1,5 @@
-import type { AgentTool, ToolResultMessage } from "@mariozechner/pi-ai";
+import type { AgentTool } from "@mariozechner/pi-agent-core";
+import type { ToolResultMessage } from "@mariozechner/pi-ai";
 import { type Static, Type } from "@sinclair/typebox";
 import { html } from "lit";
 import { createRef, ref } from "lit/directives/ref.js";