Add Integration Tests for Portfolio Analytics Flow

[Nanle-code]

Create integration tests that verify the entire portfolio analytics feature: loading account assets → calculating USD estimates → displaying allocation charts → exporting CSV. This involves multiple components and the Recharts library.

Acceptance Criteria:

• Tests verify accurate USD estimation calculations
• Chart rendering tests for different portfolio compositions
• CSV export functionality tested
• Tests handle accounts with no assets or single asset
• Tests handle price fetch failures gracefully
• Coverage for all portfolio calculation logic

[Favourof]

@Favourof has applied to work on this issue as part of the Stellar Wave Program's 5th wave.

I would like to work on this issue.

ℹ️ Repo Maintainers: To accept this application, review their application or assign @Favourof to this issue.

[Danielodingz]

@Danielodingz has applied to work on this issue as part of the Stellar Wave Program's 5th wave.

hey maintainer, please i would like to work on this issue.

ℹ️ Repo Maintainers: To accept this application, review their application or assign @Danielodingz to this issue.

[drips-wave]

Congratulations, @Favourof! 🎉 Your application was accepted by the repo's maintainers, and the issue is due on June 2, 2026.

🧑‍💻 @Favourof: Please resolve the issue such that the repo's maintainers have enough time to review your contribution before the due date. You'll earn Points for completing the issue on-time, which will make you eligible for a share of the Stellar Wave Program's reward pool.

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