feat(admin): drive write agent edits through virtual bash

[Innei]

Summary

• Replace haklex insert_node / replace_node / delete_node / search_document with a just-bash virtual workspace over /doc.xml.
• Stop injecting the full document XML into the last user message; the agent reads the working copy with cat / grep / sed.
• Diff LiteXML block ids back into the existing review overlay so edits still require user accept.
• Pin @haklex/* to 0.41.0 (optional document-tool plugins) and add just-bash.

Test plan

• pnpm exec vitest run src/vendor/rich-editor/utils/document-bash src/vendor/rich-editor/utils/image-tools.test.ts in apps/admin
• pnpm exec tsc --noEmit in apps/admin
• Open the write page, send an edit request, confirm the agent uses bash against /doc.xml instead of insert_node
• Confirm python/node stubs redirect to sed/grep/heredoc
• Confirm staged diffs appear in the editor and accept/reject still works
• Confirm a follow-up turn reseeds from the live editor (unaccepted edits are gone)