v0.79.0: escrow upload carries restic_pw_sha256 (SLICE 3 auto-confirm, agent third)

HashResticPassword = sha256 hex over the trimmed password (pinned
cross-repo vector). escrowUploadRequest gains restic_pw_sha256,omitempty
— set only when a staged password was sealed into the blob. Contract test
updated; hub mirrors next.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01PSK5g6qYLknKj8u3QAFEr6

internal/escrow/identity_test.go

@@ -97,6 +97,21 @@ func TestIdentity_RoundTrip_CarriesResticPassword(t *testing.T) {
 	}
 }
 
+// PINNED CROSS-REPO TEST VECTOR (SLICE 3): the same vector is asserted in felhom-controller — if either
+// side drifts (trailing newline, encoding, trim behavior), its half of this test fails and auto-confirm
+// can never silently mismatch. Convention: sha256 hex over the TRIMMED password string.
+func TestHashResticPassword_PinnedVector(t *testing.T) {
+	const vector = "cafef00ddeadbeef0123456789abcdef0123456789abcdef0123456789abcdef"
+	const want = "dbfc02f987e1ac0c91911d5761267089b1144628745a3343e4d96194e43c08e4"
+	if got := HashResticPassword(vector); got != want {
+		t.Fatalf("pinned vector drift: got %s want %s", got, want)
+	}
+	// trim convention: surrounding whitespace/newlines do not change the hash (both sides trim)
+	if got := HashResticPassword("  " + vector + "\n"); got != want {
+		t.Fatalf("whitespace must not change the hash (trim convention), got %s", got)
+	}
+}
+
 // AttachResticPassword: missing file → clean no-attach; staged file → trimmed value attached; empty → error.
 func TestAttachResticPassword(t *testing.T) {
 	b := &IdentityBundle{}