Rebuild agent-memory.dev as a technical showcase

[wbugitlab1]

Summary

• Rebuild the website landing route into a technical showcase for agentmemory's iii-engine runtime, memory pipeline, seeded hybrid retrieval, viewer proof, adapter surface, comparison, and quickstart.
• Extend generated website metadata so project facts include source-derived connect adapter and plugin skill counts, with fail-fast generation instead of stale fallback literals.
• Add regression coverage for website count-bearing surfaces and update task-state notes for issue Rebuild agent-memory.dev as a technical showcase #321.

Verification

• corepack pnpm exec vitest run test/tool-count-consistency.test.ts test/consistency.test.ts
• git diff --check
• git diff --cached --check
• corepack pnpm test
• corepack pnpm run build
• corepack pnpm run skills:check
• corepack pnpm run lint
• corepack pnpm --dir website run build
• Browser QA at 1440x900, 1024x768, and 390x844, including mobile menu, hero pause/resume, SearchLab, CommandCenter tabs, reduced motion, console health, and runtime external-resource checks
• semgrep scan --config p/default --error --metrics=off .
• gitleaks protect --staged --redact

Notes

• No dependency, lockfile, framework, deploy target, API, auth, schema, or persistence changes.
• OSV was not run because no dependency files, lockfiles, container images, vendored code, or third-party package surfaces changed.
• Browser clipboard writes were denied by the test runner; the quickstart copy UI surfaces CLIPBOARD BLOCKED instead of failing silently.
• Merge may trigger a public Vercel deployment outside visible repo configuration. Do not merge without a human checkpoint if that cannot be ruled out.

Closes #321