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>

start_web.sh

@@ -26,7 +26,7 @@ if [ ! -f "$PROJECT_ROOT/src/api/main_simple.py" ] || \
    [ ! -d "$PROJECT_ROOT/src/database" ]; then
     echo "❌ Not in project directory"
     echo "Please run from: $PROJECT_ROOT"
-    echo "Or use: cd /home/dell/coding/giglez && ./start_web.sh"
+    echo "Or use: cd /path/to/giglez && ./start_web.sh"
     exit 1
 fi