Refactor pipeline registry and settings

- Removed unused job_queue_type argument from PipelineRegistry class.
- Cleaned up imports in settings initialization by removing job_queue import.
- Introduced a new _backend.py file to define backend properties for easier maintenance.
- Deleted job_queue.py as it is no longer needed.
- Updated test cases to remove references to job queue configurations.
- Adjusted test assertions to reflect changes in the PipelineManager and FlowerPowerProject classes.
- Updated dependencies in the lock file, removing unused packages related to job queue management.

Author: legout

.gitignore

@@ -63,3 +63,4 @@ anypath.yaml
 package-lock.json
 docs/mkdocs/mkdocs.yml
 RUN_METHOD_ANALYSIS.md
+docs/mkdocs/site/**

CHANGELOG.md

@@ -1,5 +1,18 @@
 # Changelog
 
+## [0.21.0] - 2025-09-01
+
+### Changes
+- IMPORTANT: BREAKING CHANGES Remove job queue feature entirely from the codebase
+  - Removed job queue configuration files and settings
+  - Removed job queue logic from core modules
+  - Removed RQ-related dependencies from pyproject.toml
+  - Removed Redis and RQ services from Docker configuration
+  - Updated all tests to remove job queue functionality
+  - Updated all documentation to remove job queue references
+  - Removed job queue examples and refactored existing examples
+  - Simplified pipeline execution to direct execution only
+
 ## [0.20.0] - 2025-08-21
 
 ### Changes