feat: add MySQL Operator SEO landing page at /mysql-operator

[weicao]

Summary

• Add src/app/[locale]/mysql-operator/page.tsx — server component with SEO metadata (title, description, OpenGraph, Twitter Card, canonical URL)
• Add src/app/[locale]/mysql-operator/MysqlOperatorPage.tsx — client component with 8 sections targeting MySQL Operator search traffic

Page sections

1. Hero — headline, description, CTA buttons (Get Started, GitHub)
2. Why KubeBlocks — 4-feature value proposition grid (automated HA, PITR backup, Day-2 ops, multi-topology)
3. Topologies — SemiSync HA and MGR (Group Replication) with embedded MysqlMGRArchitectureDiagram
4. Lifecycle Features — 12-item day-2 operations grid (scaling, upgrades, monitoring, etc.)
5. Backup & Restore — PITR explanation with kubectl code snippet
6. Comparison Table — KubeBlocks vs Oracle MySQL Operator vs Percona Operator vs KubeDB
7. Quick Start — 3-step Helm install guide
8. CTA — links to docs and GitHub

Verification

• npx tsc --noEmit passes with no errors
• Default import used for MysqlMGRArchitectureDiagram (matches component export)
• import React from 'react' included to avoid JSX UMD global errors

Closes #251