feat: React frontend with landing page, browse page, and API integration

[cheangie]

Summary

Implements the complete frontend for StreamCompass using React, Vite, and React Router.

• Adds a landing page (/) with a centered search bar, debounced autocomplete against GET /search, and keyboard navigation
• Adds a browse/results page (/browse) that reads the ?q= URL param and calls POST /recommend with all active filters
• Clicking a result card fetches GET /title/{title} for full metadata (description, cast, director) displayed in a slide-up drawer
• Adds client-side routing via React Router (BrowserRouter) with a catch-all redirect to /
• Fixes browser default margin causing white border around the app via global CSS reset in index.html

Pages

Route	Component	Description
/	LandingPage.jsx	Search entry point with autocomplete dropdown
/browse	App.jsx	Results page with scrollable rows and filter bar
*	—	Redirects to /

Filters wired to /recommend

Filter	Mapped to	UI element
query	query	Search bar (nav + landing)
platforms	platforms[]	Multi-select platform chips
content_type	content_type	Type toggle (All / Movies / TV Shows)
min_imdb	min_imdb	Min IMDb toggle (Any / 6+ / 7+ / 8+ / 9+)
top_k	top_k: 40	Fixed, not exposed in UI
lambda_div	lambda_div: 0.3	Fixed, not exposed in UI

Files changed

File	Description
frontend/src/App.jsx	Browse page — API calls, filter state, result rows, detail drawer
frontend/src/LandingPage.jsx	Landing page — debounced autocomplete, search submit
frontend/src/main.jsx	React entry point — BrowserRouter and routes
frontend/index.html	CSS reset and black background
frontend/package.json	Added react-router-dom dependency
frontend/.gitignore	Added node_modules and dist

[LavishSphere]

Looks amazing otherwise.