docs: connect the open product to TMPA and FCoP

[joinwell52-AI]

What changed

• adds first-screen links to the CodeFlowMu Open product site, FCoP repository/site, TMPA repository, and the shared Digital Employee Works site
• adds a bilingual project-family table for the three public repositories
• states that CodeFlowMu Open is the installable MIT-licensed product with a PM/DEV/OPS/QA execution team and independent EVAL observer
• makes the current Cursor SDK / Cursor API Key-only provider boundary explicit

Why

CodeFlowMu Open is the product entry point of the three-repository system. Clear cross-links help product users discover the protocol and specification while preventing unsupported provider claims.

Validation

• English and Chinese README diff review
• git diff --check

Dependency alerts reported on the default branch are pre-existing and outside this documentation-only change.