docs(blog): agent MCP exact-ref weekly demo

[enricopiovesan]

Summary

• New weekly blog agent-mcp-exact-ref ("Agent speaks MCP. Exact pin kills the freestyle."): an agent calls MCP-shaped tools against the signed digits-mlp-1.0.0 exact-ref package; Browser + Node bit-identical (0→0, 7→7, 4→4, hexMatch); MCP execute matches. Freestyle → digest_mismatch / key_untrusted / rights_mismatch.
• Screenshots converted to webp under /assets/img/blog/agent-mcp-exact-ref-2026-10-09/.
• Blog index featured prepend + light llms.txt update.
• Public story stays blog-first. Links the private weekly-demos tree (access required, repo private). No public-clone CTA (.github#30).

Honesty

• Agent column is an MCP-shaped JSON-RPC façade over the published ExactModelBrowserHost under Node, not the checksum-pinned Mode A traverse-mcp binary.
• Test-only signing key; production signing is traverse#1567.
• Not Hugging Face. Not catalog model.execute.
• Swift / Kotlin / .NET exact-ref execute not claimed on the published v0.14.0 pins this demo uses. No unreleased main work.

Test plan

• cla
• governance baseline
• node --test
• playwright e2e