feat: file upload + expense report creation from Discuss attachments

- Discuss bot now reads ir.attachment from incoming messages; file-only
  messages no longer silently dropped
- ZIP files are described (contents listed) and bot asks clarifying
  question before acting; user's follow-up reply looks back for pending
  attachments so files don't need to be re-uploaded
- receipt_parser: extracts text from ZIP (recursive), JPG/PNG/etc (OCR),
  PDF (pdfplumber), HTML, TXT
- expenses_agent: full rewrite fixing broken method signatures; adds
  create_expense_sheet / create_expense / attach_receipt flow driven by
  LLM receipt parsing (Ollama, HIPAA-locked)
- master_agent: extra_context threads receipts + user_id into directives
- FastAPI /upload multipart endpoint; registered in main.py
- Odoo /ai/upload controller proxies files to agent service
- ab_ai_bot: dispatch_message_with_files() for multipart uploads

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

requirements.txt

@@ -11,3 +11,8 @@ json-log-formatter==0.5.2
 python-dotenv==1.0.1
 mcp==1.3.0
 ollama==0.3.3
+# Receipt parsing — also requires: apt install tesseract-ocr (for image OCR)
+pdfplumber==0.11.4
+Pillow==10.4.0
+pytesseract==0.3.13
+python-multipart==0.0.12