feat: implement frontend/ — Next.js frontend (Front 3)

[guidevit-dealsmartai]

Context

Part of the Application Layer design (Issue #7). Front 3 of 4.

Scope

Implement the Next.js + React frontend under frontend/. This is the public-facing web application that displays mandatário profiles, SCI scores, inconsistency cards, timelines, and patrimony charts.

Deliverables

Pages (frontend/src/app/)

Route	Description
/ (Home)	Search bar + featured mandatários (highest/lowest SCI)
/mandatario/[id]	Full profile: SCI gauge, timeline, inconsistency cards, patrimony chart
/sobre	Methodology explanation, legal basis, open-source info

Components (frontend/src/components/)

Component	Description
sci-gauge	Visual SCI score display (colored band: red/orange/yellow/green + number)
inconsistency-card	Card with FATO / MÉTRICA / FONTE sections + source links
timeline	Chronological event list (votes, expenses, declarations, contracts)
patrimony-chart	Line chart: declared wealth per election year vs cumulative salary
search-bar	Debounced autocomplete search
mandatario-summary	Card for search result lists (name, party, UF, SCI score)
nav / footer	Global navigation and footer

Tech Stack

• Next.js 15 (App Router, SSR for profile pages)
• Tailwind CSS for styling
• Recharts for patrimony chart
• TypeScript throughout

Design Language

• Clean, newspaper-like aesthetic (navy + red + gold palette)
• Monospace for data/metrics, serif for body text
• Cards with left border accent for inconsistencies
• Strictly neutral language — no emojis, no subjective adjectives
• All source links open in new tab to official government portals

Key Concerns

• SSR for profile pages (SEO — politicians should be indexable)
• Responsive design (mobile-first)
• Accessibility (WCAG 2.1 AA)
• API client in lib/api.ts (fetch wrapper for backend endpoints)
• TypeScript types in lib/types.ts matching API response schemas

Dependencies

• Depends on: Backend API (Front 2) — codes against API contract
• No Python imports — communicates via REST only

Branch

feat/10-nextjs-frontend (from develop)