Bind a manual sign-off to the tree it was given against

F63, found live on run 19. A manual check on these projects is a human
reading what the code prints. RecordPlanPhaseVerification asked only
whether a sign-off for that plan and phase existed, and one exists forever,
so rerunning a phase's automated checks at a new commit carried the human
half along with it. The rig proved it twice: two operator commits and two
re-verification requests, each coming back verified without anyone looking.

The reducer now records which tree the human confirmed, the record carries
it forward as provenance, and a run whose commit does not match it waits
for the human again. A sign-off given before any run has no confirmed tree
and still counts, so the ordinary ordering is unchanged.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01CVbaKucEYBjMqVeUgJUsc1

internal/domain/planprogress.go

@@ -55,6 +55,13 @@ type PlanPhaseRecord struct {
 	// EvidenceRef is the CAS ref of the captured command output.
 	EvidenceRef string    `json:"evidence_ref,omitempty"`
 	At          time.Time `json:"at"`
+	// ManualAtSHA is the tree a human was actually looking at when they signed
+	// this phase off. A manual check on most projects is a human reading
+	// output, so a sign-off establishes something about one tree and nothing
+	// about the next one (F63). Rerunning the automated half re-establishes it
+	// at the new commit; the manual half has to be given again, and this is
+	// what makes the difference visible instead of assumed.
+	ManualAtSHA string `json:"manual_at_sha,omitempty"`
 }
 
 // Stale reports whether the tree has moved since this phase was verified. A