feat: Add bundle analyzer for build optimization

Description

Install and configure Next.js bundle analyzer to identify large dependencies and optimize bundle size.

Problem

• No visibility into bundle composition
• Unknown which dependencies are increasing bundle size
• No metrics for code splitting effectiveness
• Difficult to identify optimization opportunities

Current Dependencies

Some potentially large dependencies:

• framer-motion - Animation library
• highlight.js - Syntax highlighting
• marked - Markdown parser
• lucide-react - Icon library
• Various other dependencies

Proposed Solution

Add @next/bundle-analyzer to:

• Visualize bundle composition
• Identify large dependencies
• Find duplicate code
• Optimize code splitting
• Track bundle size over time

Acceptance Criteria

• Install @next/bundle-analyzer
• Configure in next.config.mjs
• Add npm script: npm run analyze
• Document bundle analysis process
• Create baseline bundle size report
• Add bundle size to PR checks (optional)
• Document findings and optimization recommendations

Files to Modify

• package.json - Add dependency and script
• next.config.mjs - Configure analyzer
• docs/bundle-analysis.md - New documentation

Start with package.json and next.config.mjs to review the existing scripts and Next.js configuration. Add the analyzer dependency and npm script, then create docs/bundle-analysis.md describing how to run analysis. Done means the analyzer is configured, the command works, and a baseline bundle size report and optimization findings are documented.