feat: add semantic search to spotlight

[mattkrick]

Description

• Adds PGVector to our postgres DB (it's already generally available in DO and GCP, the SQL files here are just for local dev)
• Adds semantic search to spotlight as a POC

Demo

[If possible, please include a screenshot or gif/video, it'll make it easier for reviewers to understand the scope of the changes and how the change is supposed to work. If you're introducing something new or changing the existing patterns, please share a Loom and explain what decisions you've made and under what circumstances]

Testing scenarios

Final checklist

• I checked the code review guidelines
• I have added Metrics Representative as reviewer(s) if my PR invovles metrics/data/analytics related changes
• I have performed a self-review of my code, the same way I'd do it for any other team member
• I have tested all cases I listed in the testing scenarios and I haven't found any issues or regressions
• Whenever I took a non-obvious choice I added a comment explaining why I did it this way
• I added the label One Review Required if the PR introduces only minor changes, does not contain any architectural changes or does not introduce any new patterns and I think one review is sufficient'
• PR title is human readable and could be used in changelog

[github-actions]

This PR exceeds the recommended size of 1000 lines. Please make sure you are NOT addressing multiple issues with one PR. Note this PR will be delayed and might be rejected due to its size.

[github-actions]

This PR exceeds the recommended size of 1000 lines. Please make sure you are NOT addressing multiple issues with one PR. Note this PR will be delayed and might be rejected due to its size.

[github-actions]

This PR exceeds the recommended size of 1000 lines. Please make sure you are NOT addressing multiple issues with one PR. Note this PR will be delayed and might be rejected due to its size.

[github-actions]

This PR exceeds the recommended size of 1000 lines. Please make sure you are NOT addressing multiple issues with one PR. Note this PR will be delayed and might be rejected due to its size.