chore(llm-observability): Dashboard polish

[Twixes]

Changes

A few tweaks to and around the LLM observability dashboard:

• the "Traces" graph is now first on the dashboard, and "Generative AI users" is second – this is because traces are always going to be accurate, while user counts do come with the caveat of requiring distinct_id instrumentation
• better responsiveness (including container queries)
• column configurator enabled in Generations, and the default columns are cleaned up
• more robust demo data

[k11kirky]

Looks Great

[github-actions]

Size Change: 0 B

Total Size: 1.13 MB

ℹ️ View Unchanged

Filename	Size
frontend/dist/toolbar.js	1.13 MB

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[posthog-bot]

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• chromium: 0 added, 2 modified, 0 deleted (diff for shard 2)
• webkit: 0 added, 0 modified, 0 deleted

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