Trim stale project documentation

[stevenmunn312-tech]

Summary

• reduce always-loaded agent guidance to durable commands and invariants
• replace completed-work transcripts with active-only todo lists
• remove the closed T-HMI integration plan and repair documentation routing/evidence references

Validation

• all relative Markdown links resolve across the repository
• auto-memory marker counts and config validated
• git diff whitespace check passes (line-ending notices only)

Base is Hardware; this does not cross the frozen main boundary.