fix: wrap tool handler results in MCP content blocks (#4)

[smichaelsen]

Summary

Fixes #4. Every tool handler in src/tools/*.ts returned the raw Paperless API response directly. MCP requires CallToolResult shape { content: [{ type, text }, ...] } — bare objects pass the SDK at runtime but compliant clients (Claude Code) silently render an empty result.

Adds a shared toTextResult(data) helper in src/tools/result.ts and threads it through every handler in documents, tags, correspondents, and documentTypes.

Notes

• download_document returns { blob, filename } stringified into the text block. A resource-typed content block would be more correct for binary data but is out of scope here.
• The searchDocuments token-efficiency stripping (PR Improve search context efficiency to prevent token overflow nloui/paperless-mcp#13) lives in PaperlessAPI.ts and is unaffected.

Test

Smoke-tested against the live Paperless-NGX instance via the reproducer from #4:

printf '%s\n%s\n' \
  '{"jsonrpc":"2.0","id":1,"method":"initialize","params":{"protocolVersion":"2024-11-05","capabilities":{},"clientInfo":{"name":"t","version":"1"}}}' \
  '{"jsonrpc":"2.0","id":2,"method":"tools/call","params":{"name":"list_tags","arguments":{}}}' \
  | node build/index.js <url> <token>

Result: result.content[0].type === "text", content[0].text contains the JSON-stringified Paperless payload (83 tags). ✅

Test plan for reviewer

• Pull, npm run build, restart MCP client
• Run list_tags / list_correspondents / list_document_types / search_documents — results should now render in the client instead of appearing empty
• update_document, create_*, bulk_edit_* — confirm they still take effect and return their (now-visible) response

🤖 Generated with Claude Code