fix(frontend): correct state mutation in GapAnalysis

[PRAteek-singHWY]

Summary

The Map Analysis page currently updates gapAnalysis state by mutating the existing object and forcing a re-render via a temporary undefined state. This pattern breaks React’s immutability guarantees and relies on a workaround that can lead to unnecessary renders and harder-to-reason-about behavior.

What Changed

This PR replaces the direct state mutation with an immutable update using the functional setState pattern. The new approach creates a fresh state object when weak links are loaded, allowing React to re-render correctly without forcing intermediate state resets.

Why This Matters

• Removes a known React anti-pattern (explicitly called out in the code comment)
• Avoids forced re-renders and potential race conditions
• Improves maintainability and correctness without changing user-visible behavior
• Keeps the change tightly scoped to state management only

Scope

• UI-only change
• No backend or API changes
• No behavior or layout changes beyond the internal state update