feat: add aspects charts

[Henrrypg]

This pull request standardizes how LLM (Large Language Model) usage data (such as token counts) is captured, serialized, and emitted in workflow events and API responses throughout the codebase. It replaces the previous tokens_used field with a more comprehensive usage dictionary/object, ensures this data is JSON-serializable for xAPI tracking, and updates orchestrators and tests accordingly.

LLM Usage Data Handling and Serialization:

• Replaces the tokens_used field with a usage dictionary/object in all LLM processor responses and orchestrators, ensuring richer and more flexible usage tracking. [1] [2] [3] [4] [5] [6]
• Adds a _convert_usage_to_json_serializable method to BaseOrchestrator to handle serialization of usage data, including support for Pydantic models, so that all emitted event payloads are JSON-serializable.

Workflow Event Emission and xAPI Integration:

• Modifies all orchestrators to emit workflow events with the new usage field, and updates the event emission logic to include usage data only when present. [1] [2] [3] [4] [5]
• Adds a new xAPI extension constant for usage data and updates the xAPI transformer to include usage information in the event extensions if available. [1] [2]

Testing Updates:

• Expands and adds tests to verify correct event emission, including context handling, usage serialization (including Pydantic objects), and ensures that the usage field is only included when appropriate.
• Updates or removes references to the deprecated tokens_used and model_used metadata fields in orchestrator and LLM processor tests. [1] [2] [3] [4]

Charts

1. Total Tokens By Course

2. Event Count by Workflow

3. Daily Token Consumption Trend

4. Unique Users by Course

5. Event Count by Verb

[openedx-webhooks]

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[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 94.33%. Comparing base (35df7a4) to head (9b3d2ac).
⚠️ Report is 23 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #193      +/-   ##
==========================================
- Coverage   94.34%   94.33%   -0.01%     
==========================================
  Files          60       60              
  Lines        6858     6846      -12     
  Branches      370      370              
==========================================
- Hits         6470     6458      -12     
  Misses        296      296              
  Partials       92       92              

Flag	Coverage Δ
unittests	94.33% <ø> (-0.01%)	⬇️

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