feat(documents): add document processing capability (U1-U9)
Implements end-to-end document generation, template filling, and reading:
- DocumentService: unified business layer for create/query/download
- Renderers: Word (Markdown->docx), Excel (Markdown/JSON->xlsx),
PDF (Markdown->pdf with CJK font), Template (Jinja2 sandbox .docx fill)
- DocumentLoader: read PDF/Word/Excel/Markdown/HTML/text -> Document
- DocumentTool: Agent tool with action=create|read
- REST API: /api/v1/documents (create, upload-template, list, download)
- Frontend: DocumentPanel, DocumentCard, documents Pinia store,
chat store tool_result detection
- Security: path traversal guard (Path.resolve + relative_to),
SSTI guard (SandboxedEnvironment), API key auth, 50MB upload limit
- Bug fixes: template path traversal (400 not 500), TemplateRenderer
lazy-load (no external registration dependency)
- Tests: 168 tests (unit + security + E2E F1/F2/F3 + bug hunt)
- Docs: README section 17, requirements + plan + test-plan docs
Requirements R1-R28 verified, F1-F3 user flows pass.
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