Document Milestone 17 resume checkpoint

[jmjava]

Summary

• mark Milestone 17 as intentionally paused after M17.10
• record completed and remaining slices
• document the exact next-month resume order and terminal conditions
• call out the default-branch prerequisite for the first strict Results workflow dispatch
• backfill completion evidence for M17.6 through M17.10

Verification

• Markdown diff checked for whitespace errors
• documentation-only change; no runtime behavior changed