fix(docs): resolve mermaid syntax errors

[Kairos-T]

Description of the Change

Problem

A Mermaid diagram in backend/docs/flow_execution.md does not render in the Markdown preview due to invalid Note over syntax:

Unable to render rich display

Parse error on line 21:
... Note over AssistantUA,Ass
----------------------^
Expecting 'SEMI', 'NEWLINE', 'EOF', 'AMP', 'START_LINK', 'LINK', 'LINK_ID', got 'NODE_STRING'

For more information, see https://docs.github.com/get-started/writing-on-github/working-with-advanced-formatting/creating-diagrams#creating-mermaid-diagrams

Note over is a sequence diagram directive and is not valid in graph TD (flowchart) diagrams.

Solution

Replaced the two invalid Note over statements with standard flowchart node definitions:

Note over AssistantUA,AssistantDirect: ... -> AssistantNote[Operates independently<br/>from Task/Subtask hierarchy]
Note over Adviser: ... -> AdviserNote["Also used for:<br/>- Mentor (execution monitoring)<br/>- Planner (task planning)"]

None.

Type of Change

• 🐛 Bug fix (non-breaking change which fixes an issue)
• 📚 Documentation update

Areas Affected

• Documentation

Testing and Verification

Test Steps

1. Verified the syntax error on GitHub
2. Fixed the syntax errors
3. Verified that the flowchart diagram renders without parse errors

Test Results

Diagrams render successfully after the fix. No parse errors produced by either affected code block.

Security Considerations

None.

Performance Impact

None.

Documentation Updates

• Other: Fixed Mermaid syntax in backend/docs/flow_execution.md

Deployment Notes

None

Checklist

Code Quality

Compatibility

• Changes are backward compatible

Documentation

• Documentation is clear and complete
• Comments are added for non-obvious code

Additional Notes