Pull Request: Feature and Test Enhancements

Summary of Changes

Closes #807 [TEST] Fuzz Test File Upload Validation
Added fast-check property-based fuzz testing suite in tests/fuzz/upload.fuzz.test.ts.
Validates random file names, extensions, declared MIME types, magic byte headers, and 500 MB boundary file sizes across 1000 generated cases.

Closes #808 [TEST] Add Playwright Visual Regression Tests
Added visual regression testing suite in tests/e2e/visual.spec.ts.
Configured snapshot baseline path tests/visual-baselines/ and max diff pixel ratio threshold of 1% (maxDiffPixelRatio: 0.01).
Added NPM scripts test:visual and test:visual:update.
Captures visual baselines for dashboard, projects (with clips), wallet portfolio, and earnings table.

Closes #809 [FEAT] Add Clip Quality Score Breakdown Tooltip
Extended clip data model with scoreBreakdown: { hook: number, retention: number, emotional: number, trending: number }.
Updated AI backend callback schema and job store payload processing.
Created ScoreBreakdownTooltip component showing mini bars for hook, retention, emotional, and trending sub-scores.
Made tooltip keyboard accessible (tabIndex={0}, focus/blur triggers, ARIA attributes).
Added Storybook story in components/projects/ScoreBreakdownTooltip.stories.tsx.

Closes #810 [FEAT] Add StellarWalletProvider and EmbeddedWalletProvider Components
Created EmbeddedWalletProvider exposing { wallet, isLoading, error } context and useEmbeddedWallet hook.
Updated StellarWalletProvider to call CryptoSaltInitializer on mount and wrap children in EmbeddedWalletProvider.
Ensured SSR safety on both providers.
Created comprehensive unit tests in __tests__/components/StellarWalletProvider.test.tsx verifying wallet creation and retrieval.

Naming conventions: ensure files, components, types, variables, and hooks follow the project's naming conventions (see docs/naming-conventions.md).
- Files: kebab-case
- Components/Types: PascalCase
- Variables/Functions: camelCase
- Hooks: start with use