SPEC.md: bring §13 git history current

Append the three commits missing from the block: the previous handoff
note 761c4dd, the docker-compose port bump fd2f0df, and the doc
reorganisation c5eef6a.

SPEC.md

@@ -669,6 +669,9 @@ before acting — nothing here is load-bearing once it grows stale.
 ## 13. Git history (as of this writing)
 
 ```
+c5eef6a Docs: rename HANDOFF.md to SPEC.md, add admin manual, refresh README
+fd2f0df changed docker compose port
+761c4dd HANDOFF.md: note stepper close via direct listeners on Phase 17
 e93df6b Fix: stepper close via direct element listeners (not doc delegation)
 ac6ae73 HANDOFF.md: note number-stepper rebuild on Phase 17
 ff807c2 Rewrite: number-stepper popover from scratch