Tweaks to prompts to ensure proper table selection and SQL generation

[codecov[bot]]

Codecov Report

Attention: Patch coverage is 44.44444% with 5 lines in your changes missing coverage. Please review.

Project coverage is 61.10%. Comparing base (afdac6a) to head (2dd88cf). Report is 1 commits behind head on main.

Files with missing lines	Patch %	Lines
lumen/ai/agents.py	40.00%	3 Missing :warning:
lumen/ai/ui.py	33.33%	2 Missing :warning:

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #769 +/- ## ========================================== + Coverage 61.05% 61.10% +0.04% ========================================== Files 103 103 Lines 12515 12499 -16 ========================================== - Hits 7641 7637 -4 + Misses 4874 4862 -12 ```

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