Implement Release 1 metadata workflow

[alianjum0]

Summary

• add URL and pasted-HTML metadata analysis
• add deterministic SEO/social audit scoring and bounded image inspection
• add editable metadata, live previews, generated tags, and responsive UI
• document the Release 1 behavior and security boundaries

Validation

• pnpm test — 44 passed, 0 failed
• pnpm install --frozen-lockfile — passed
• pnpm audit --prod --audit-level=high — no known vulnerabilities
• JavaScript syntax checks — passed
• git diff --check — passed
• desktop and 390x844 browser checks — passed with no console warnings/errors
• public URL smoke test against example.com — passed

Risks and limits

• image inspection supports JPEG, PNG, GIF, and WebP
• JavaScript is required for live editing and copying; server-rendered analysis remains usable
• this PR does not deploy the application or implement Releases 2 and 3