Replace window.reload with proper state refresh after funding

[0xdevcollins]

Problem

After a successful pledge in `funding-modal.tsx`, the page does `window.location.reload()` to reflect the new funding state. This breaks the SPA experience, loses scroll position, and causes a jarring full-page refresh.

Current Code

// After successful pledge
window.location.reload();

Expected Behavior

• Use React state management to refresh funding data after pledge
• Invalidate relevant queries (e.g., campaign data, funding progress, backers list)
• Show updated funding progress bar immediately
• Maintain scroll position and UI state
• Consider optimistic update: show new amount immediately, reconcile with server

Implementation

• If using React Query / SWR: invalidate campaign and contributions queries
• If using local state: re-fetch via `getCampaignOnChain()` and update sidebar
• Add `onSuccess` callback prop to `FundingModal` to notify parent

Acceptance Criteria

• No full page reload after pledge
• Funding progress updates immediately
• Backers list refreshes
• Scroll position maintained

Priority

Low — Functional but poor UX.

Labels

crowdfunding, ui, ux

[linear]

BOU-173