feat: Add event emission for external grader scores

This commit adds the EXTERNAL_GRADER_SCORE_SUBMITTED event emission to the
put_result endpoint in the XQueueViewSet. When a grader submits a result and
the score is successfully saved, the system now emits an event with all the
necessary information for the LMS to render the graded XBlock.

Key changes:
- Add queue_key field to ExternalGraderDetail model
- Include queue_key in create_external_grader_detail method
- Emit EXTERNAL_GRADER_SCORE_SUBMITTED event after successful score update
- Implement robust false to propagate error and put submission in pending queue again
- Add migration for the new queue_key field
- Add openedx-events dependency

This enables the event-driven approach for updating XBlocks with scoring data
from the edx-submissions service, supporting the gradual migration away from
HTTP-based XQueue callbacks.

Author: leoaulasneo98

docs/source/decisions/0004-transaction-handling-in-get_submission

@@ -0,0 +1,33 @@
+Improving Transaction Handling in Get Submission
+================================================
+
+Status
+------
+
+**Provisional** *2025-03-19*
+
+Context
+-------
+
+We identified a concurrency issue in the submission processing flow. Multiple instances of the xqueue watcher were processing the same transaction simultaneously, causing duplicate handling of submissions. Additionally, submissions remained stuck in the "pulled" state indefinitely when errors or unexpected interruptions occurred during processing.
+
+Decision
+--------
+
+We introduced a robust locking mechanism at the database level to prevent concurrent processing of the same submission. Specifically, we employed database row-level locking (`select_for_update(nowait=True)`) on submissions to ensure only one xqueue watcher instance can process a transaction at a time. Additionally, we implemented a timeout-based fallback, marking submissions in the "pulled" state as available again if they exceed a defined timeout period (5 minutes).
+
+Consequences
+------------
+
+Positive
+~~~~~~~~
+
+- Ensures data consistency by preventing duplicate transaction processing.
+- Implements automatic recovery for submissions stuck in the "pulled" state, improving overall system reliability.
+- Minimal impact on system performance due to efficient database-level locking.
+
+Negative
+~~~~~~~~
+
+- Slightly increased complexity in transaction handling logic.
+- Potential minor latency increase when contention occurs due to database locks.

requirements/base.txt

@@ -1,32 +1,16 @@
 #
-# This file is autogenerated by pip-compile with Python 3.12
+# This file is autogenerated by pip-compile with Python 3.11
 # by the following command:
 #
 #    make upgrade
 #
 asgiref==3.8.1
-    # via django
 django==4.2.21
-    # via
-    #   -c /home/runner/work/edx-submissions/edx-submissions/requirements/common_constraints.txt
-    #   -r requirements/base.in
-    #   django-model-utils
-    #   djangorestframework
-    #   edx-django-release-util
-    #   jsonfield
 django-model-utils==5.0.0
-    # via -r requirements/base.in
 djangorestframework==3.16.0
-    # via -r requirements/base.in
 edx-django-release-util==1.5.0
-    # via -r requirements/base.in
 jsonfield==3.1.0
-    # via -r requirements/base.in
 pytz==2025.2
-    # via -r requirements/base.in
 pyyaml==6.0.2
-    # via edx-django-release-util
 six==1.17.0
-    # via edx-django-release-util
 sqlparse==0.5.3
-    # via django

requirements/ci.txt

@@ -1,69 +1,25 @@
 #
-# This file is autogenerated by pip-compile with Python 3.12
+# This file is autogenerated by pip-compile with Python 3.11
 # by the following command:
 #
 #    make upgrade
 #
 cachetools==5.5.2
-    # via
-    #   -r /home/runner/work/edx-submissions/edx-submissions/requirements/tox.txt
-    #   tox
 certifi==2025.4.26
-    # via requests
 chardet==5.2.0
-    # via
-    #   -r /home/runner/work/edx-submissions/edx-submissions/requirements/tox.txt
-    #   tox
 charset-normalizer==3.4.2
-    # via requests
 colorama==0.4.6
-    # via
-    #   -r /home/runner/work/edx-submissions/edx-submissions/requirements/tox.txt
-    #   tox
 coverage[toml]==7.8.0
-    # via coveralls
 coveralls==4.0.1
-    # via -r requirements/ci.in
 distlib==0.3.9
-    # via
-    #   -r /home/runner/work/edx-submissions/edx-submissions/requirements/tox.txt
-    #   virtualenv
 docopt==0.6.2
-    # via coveralls
 filelock==3.18.0
-    # via
-    #   -r /home/runner/work/edx-submissions/edx-submissions/requirements/tox.txt
-    #   tox
-    #   virtualenv
 idna==3.10
-    # via requests
 packaging==25.0
-    # via
-    #   -r /home/runner/work/edx-submissions/edx-submissions/requirements/tox.txt
-    #   pyproject-api
-    #   tox
 platformdirs==4.3.8
-    # via
-    #   -r /home/runner/work/edx-submissions/edx-submissions/requirements/tox.txt
-    #   tox
-    #   virtualenv
 pluggy==1.5.0
-    # via
-    #   -r /home/runner/work/edx-submissions/edx-submissions/requirements/tox.txt
-    #   tox
 pyproject-api==1.9.1
-    # via
-    #   -r /home/runner/work/edx-submissions/edx-submissions/requirements/tox.txt
-    #   tox
 requests==2.32.3
-    # via coveralls
 tox==4.25.0
-    # via -r /home/runner/work/edx-submissions/edx-submissions/requirements/tox.txt
 urllib3==2.2.3
-    # via
-    #   -c /home/runner/work/edx-submissions/edx-submissions/requirements/common_constraints.txt
-    #   requests
 virtualenv==20.31.2
-    # via
-    #   -r /home/runner/work/edx-submissions/edx-submissions/requirements/tox.txt
-    #   tox

requirements/common_constraints.txt

@@ -3,6 +3,16 @@
 # See BOM-2721 for more details.
 # Below is the copied and edited version of common_constraints
 
+# This is a temporary solution to override the real common_constraints.txt
+# In edx-lint, until the pyjwt constraint in edx-lint has been removed.
+# See BOM-2721 for more details.
+# Below is the copied and edited version of common_constraints
+
+# This is a temporary solution to override the real common_constraints.txt
+# In edx-lint, until the pyjwt constraint in edx-lint has been removed.
+# See BOM-2721 for more details.
+# Below is the copied and edited version of common_constraints
+
 # A central location for most common version constraints
 # (across edx repos) for pip-installation.
 #