feat: add ui for assets page

[Jetshree]

What does this PR change?

• This PR implements a complete Assets page for the OpenCost UI with comprehensive cost visualization and analysis capabilities.

Does this PR relate to any other PRs?

• No

How will this PR impact users?

• Provides visualization for assets cost.

Does this PR address any GitHub or Zendesk issues?

• Closes ... [LFX Mentorship Term 1 2026] OpenCost UI Revamp #155 Support Assets in the UI #28

How was this PR tested?

• Verified all charts render correctly with mock data. All files compile without errors

Does this PR require changes to documentation?

• Yes

Have you labeled this PR and its corresponding Issue as "next release" if it should be part of the next OpenCost release? If not, why not?

• Yes, this PR should be labeled as "next release" if accepted.

[netlify]

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