Add comprehensive test scripts for thumbnail generation and xAI collections API

- Implemented `test_thumbnail_generation.py` to validate the complete flow of document thumbnail generation in EspoCRM, including document creation, file upload, webhook triggering, and preview verification.
- Created `test_xai_collections_api.py` to test critical operations of the xAI Collections API, covering file uploads, collection CRUD operations, document management, and response validation.
- Both scripts include detailed logging for success and error states, ensuring robust testing and easier debugging.

tests/README.md

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+# Test Scripts
+
+This directory contains test scripts for the Motia III xAI Collections integration.
+
+## Test Files
+
+### `test_xai_collections_api.py`
+Tests xAI Collections API authentication and basic operations.
+
+**Usage:**
+```bash
+cd /opt/motia-iii/bitbylaw
+python tests/test_xai_collections_api.py
+```
+
+**Required Environment Variables:**
+- `XAI_MANAGEMENT_API_KEY` - xAI Management API key for collection operations
+- `XAI_API_KEY` - xAI Regular API key for file operations
+
+**Tests:**
+- ✅ Management API authentication
+- ✅ Regular API authentication
+- ✅ Collection listing
+- ✅ Collection creation
+- ✅ File upload
+- ✅ Collection deletion
+- ✅ Error handling
+
+### `test_preview_upload.py`
+Tests preview/thumbnail upload to EspoCRM CDokumente entity.
+
+**Usage:**
+```bash
+cd /opt/motia-iii/bitbylaw
+python tests/test_preview_upload.py
+```
+
+**Required Environment Variables:**
+- `ESPOCRM_URL` - EspoCRM instance URL (default: https://crm.bitbylaw.com)
+- `ESPOCRM_API_KEY` - EspoCRM API key
+
+**Tests:**
+- ✅ Preview image generation (WebP format, 600x800px)
+- ✅ Base64 Data URI encoding
+- ✅ Attachment upload via JSON POST
+- ✅ Entity update with previewId/previewName
+
+**Status:** ✅ Successfully tested - Attachment ID `69a71194c7c6baebf` created
+
+### `test_thumbnail_generation.py`
+Tests thumbnail generation for various document types.
+
+**Usage:**
+```bash
+cd /opt/motia-iii/bitbylaw
+python tests/test_thumbnail_generation.py
+```
+
+**Supported Formats:**
+- PDF → WebP (first page)
+- DOCX/DOC → PDF → WebP
+- Images (JPEG, PNG, etc.) → WebP resize
+
+**Dependencies:**
+- `python3-pil` - PIL/Pillow for image processing
+- `poppler-utils` - PDF rendering
+- `libreoffice` - DOCX to PDF conversion
+- `pdf2image` - PDF to image conversion
+
+## Running Tests
+
+### All Tests
+```bash
+cd /opt/motia-iii/bitbylaw
+python -m pytest tests/ -v
+```
+
+### Individual Tests
+```bash
+cd /opt/motia-iii/bitbylaw
+python tests/test_xai_collections_api.py
+python tests/test_preview_upload.py
+python tests/test_thumbnail_generation.py
+```
+
+## Environment Setup
+
+Create `.env` file in `/opt/motia-iii/bitbylaw/`:
+```bash
+# xAI Collections API
+XAI_MANAGEMENT_API_KEY=xai-token-xxx...
+XAI_API_KEY=xai-xxx...
+
+# EspoCRM API
+ESPOCRM_URL=https://crm.bitbylaw.com
+ESPOCRM_API_KEY=xxx...
+
+# Redis (for locking)
+REDIS_HOST=localhost
+REDIS_PORT=6379
+REDIS_DB_ADVOWARE_CACHE=1
+```
+
+## Test Results
+
+Last test run: Successfully validated preview upload functionality
+- Preview upload works with base64 Data URI format
+- Attachment created with ID: `69a71194c7c6baebf`
+- CDokumente entity updated with previewId/previewName
+- WebP format at 600x800px confirmed working