fix(agent): replace jsdom with linkedom to fix Docker EISDIR error (#186)

jsdom relies on Node.js-specific APIs that Bun cannot properly resolve
when running a bundled artifact. This caused an EISDIR error in Docker
containers (Bun tried to read the jsdom directory as a file).

Replace jsdom with linkedom, a lightweight pure-JS DOM implementation
that is fully compatible with Bun and @mozilla/readability. Also remove
the --external jsdom build flag since linkedom bundles cleanly.

Closes #181

packages/agent/src/tools/web.ts

@@ -1,7 +1,7 @@
 import { tool } from 'ai'
 import { z } from 'zod'
 import { Readability } from '@mozilla/readability'
-import { JSDOM } from 'jsdom'
+import { parseHTML } from 'linkedom'
 import TurndownService from 'turndown'
 
 const turndownService = new TurndownService()
@@ -76,8 +76,8 @@ export const getWebTools = () => {
 
           case 'markdown': {
             try {
-              const dom = new JSDOM(content, { url })
-              const reader = new Readability(dom.window.document)
+              const { document } = parseHTML(content)
+              const reader = new Readability(document as unknown as Document)
               const article = reader.parse()
 
               if (!article || !article.content) {