security: sanitize personal paths and usernames from documentation

Replaced all instances of:
- /home/dell/coding/giglez → /path/to/giglez
- /home/dell → ~
- leetcrypt → your-username
- PreistlyPython → your-username
- dell@ → user@

Affected files:
- 17 documentation files in docs/
- 2 shell scripts (download_rf_test_datasets.sh, start_web.sh)

No functional changes, only path/username sanitization for privacy.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

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

docs/TESTING_READY.md

@@ -124,7 +124,7 @@ All testing infrastructure committed:
 pip install pytest pytest-asyncio
 
 # Run GPS validator tests
-cd /home/dell/coding/giglez
+cd /path/to/giglez
 pytest tests/unit/test_gps_validator.py -v
 
 # Expected: All 20+ tests pass
@@ -366,7 +366,7 @@ Create `TESTING_RESULTS.md` during testing:
 
 ```bash
 # Local machine - Quick test
-cd /home/dell/coding/giglez
+cd /path/to/giglez
 pip install pytest pytest-asyncio
 pytest tests/unit/test_gps_validator.py -v