docs: add The Context Company observability integration

[rohilvagarwal]

What this changes

• Adds a dedicated The Context Company observability guide.
• Adds The Context Company to the observability overview and AgentOS external-provider list.
• Publishes the merged cookbook example in the examples section.
• Adds the provider and example pages to navigation.

The runnable example was added to agno-agi/agno in agno-agi/agno#8955. This PR makes that integration discoverable in the public documentation.

Verification

• mint broken-links
• Parsed docs.json with jq
• Previewed the provider guide, example, observability overview, and Agent Observability page locally

[kausmeows]

Thanks for adding this!