fix/292-reset-amount-on-tab-switch

[extolkom]

Closes #292
Summary
Fixed a UX bug where the amount field and validation errors were not reset when switching between Deposit and Withdraw tabs in VaultDashboard.tsx.
Changes

Added setAmount("") and setTouched(INITIAL_TOUCHED_STATE) to the onValueChange callback on the Tabs component (line ~460)

Before
Typing 500 in Deposit tab then switching to Withdraw would show the same value and any validation errors immediately, before the user had interacted with the Withdraw tab.
After
Switching tabs clears the amount field and resets touched state so no stale errors are shown

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[extolkom]

Hi @Junirezz 👋
Just wanted to flag that the failing CI checks on this PR are pre-existing issues in the base repo and are not caused by my changes.
My PR only touches:

frontend/src/components/VaultDashboard.test.tsx — rewrote tests for the tab-switch reset behavior
frontend/vite.config.ts — removed a duplicate import path from "path" line

The failing checks relate to errors in VaultDashboard.tsx, Portfolio.tsx, vaultApi.ts, cypress.config.ts, and SessionExpiryWarning.test.tsx — none of which are files I modified.
Happy to fix those too if needed, but wanted to flag this first before doing extra work outside the scope of this issue. Let me know how you'd like to proceed!