docs: Update architecture documentation with comprehensive details

[deepsm007]

Enhance the architecture page with detailed system architecture documentation:

• High-level architecture diagrams
• Component architecture (webhook flow, job execution, plugin system)
• Deployment architecture diagrams
• Controller architecture details
• Component interaction diagrams
• Key design patterns (Kubernetes native, controller pattern, plugin architecture)
• Security architecture
• Scalability considerations
• Monitoring and observability

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[k8s-ci-robot]

[APPROVALNOTIFIER] This PR is NOT APPROVED

This pull-request has been approved by: deepsm007
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[k8s-ci-robot]

Hi @deepsm007. Thanks for your PR.

I'm waiting for a github.com member to verify that this patch is reasonable to test. If it is, they should reply with /ok-to-test on its own line. Until that is done, I will not automatically test new commits in this PR, but the usual testing commands by org members will still work. Regular contributors should join the org to skip this step.

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[matthyx]

/ok-to-test

[stmcginnis]

This does look useful. It would be good to clean up some of the LLM cruft with these though so they aren't overly verbose and redundant.

/lgtm