feat(site): release portable snapshots and SEO audits in v0.2.0

[Deniffer001]

gkit can now capture public page facts into portable snapshot directories, audit them offline, and compare two observations without maintaining a site database. This releases the project-independent site command group in v0.2.0.

• Discover sitemap routes with preserved XML/HTTP evidence and explicit partial coverage.
• Capture public HTTP responses or the supplied Nuxt build: read prerendered HTML and run its SSR artifact where needed. Preserve exact source references, build digest, capture conditions, JSONL fields and original HTML.
• Audit and diff snapshots offline. Failed observations and incompatible conditions remain unknown/incomparable rather than implying a fix.
• Optionally explain a bounded page diff against two exact Git trees using the caller's Grok installation; only disposable explanation cache lives under the profile.

Profiles supply site origins, routes, rules and repository identity. No Tripo configuration/data, scheduler, warehouse destination or project-specific CI orchestration is included. Existing argc v7.11.1 from main is retained.

Validation: 190 tests, 15 CLI scenarios, typecheck, 40 contract evaluation tasks, independent package installation, and a real Nuxt prerender/SSR fixture. The archive was inspected for project-specific material and repacked with identical SHA-256. The release workflow additionally checks the public installation's site schema.

Limits: no browser hydration/performance audit, historical CMS replay or served-revision attestation. Live Grok execution was tested with a fixture subprocess; no paid model call was made. Consumers own scheduling and long-term retention.