Clarify roadmap ownership and sequencing

[deverman]

Summary

• make the execution plan the only canonical delivery sequence
• insert issue Mark active and on-hold projects reviewed through edit_projects #138 after Support dropping and restoring OmniFocus tasks without recording completion #129 and before workflow research and creation work
• replace duplicate and stale roadmap sections with links to the canonical plan

Validation

• swift run focusrelay-dev validate --impact docs
• git diff --check

The documented --base option is not accepted by the current focusrelay-dev helper, so the supported docs impact command was used.