fix(auth): wire RevokeAllForActor + RotateCSRFToken to mutation paths

Closes HIGH-1 + HIGH-2 of the 2026-05-10 audit.

HIGH-1: breakglass.Service.SetPassword and RemoveCredential now call
sessions.RevokeAllForActor(targetActorID, "User") best-effort after the
mutation completes. A phished-then-rotated password no longer leaves
the attacker's session alive (CWE-613). Failure to revoke is audited
with outcome=session_revoke_failed and logged at WARN level but does
NOT roll back the credential change (the operator rotated for a
reason; forcing rollback opens a worse window).

- breakglass.SessionMinter interface extended with RevokeAllForActor.
- cmd/server/main.go::breakglassSessionMinterAdapter gains the bridge
  to session.Service.RevokeAllForActor.
- stubSessions in service_test.go tracks revokeAllIDs / revokeAllTypes
  / revokeAllErr.
- Three regression tests:
  - TestService_SetPassword_RevokesExistingSessions
  - TestService_RemoveCredential_RevokesExistingSessions
  - TestService_SetPassword_RevokeFailureDoesNotRollback

HIGH-2: New session.Service.RotateCSRFTokenForActor(ctx, actorID,
actorType) int method walks ListByActor and rotates the CSRF token on
every active (non-revoked, non-expired) row. Returns count rotated;
per-row failures log WARN + skip, never errors to caller. New
handler.CSRFRotator interface + AuthHandler.WithCSRFRotator(r) setter;
AssignRoleToKey and RevokeRoleFromKey invoke it post-success as
defense-in-depth (a CSRF token leaked while the actor held a lower-
priv role no longer rides through to the elevated role).

- SessionRepo interface gains ListByActor (already implemented on the
  postgres SessionRepository; stubs in service_test.go + bench_test.go
  updated to match).
- cmd/server/main.go calls .WithCSRFRotator(sessionService) on the
  AuthHandler.
- Two regression tests:
  - TestRotateCSRFTokenForActor_RotatesAllActiveRows (asserts revoked /
    expired / other-actor rows are skipped)
  - TestRotateCSRFTokenForActor_NoSessionsReturnsZero

Verification gate green: gofmt clean, go vet clean, go test -short
-count=1 ./internal/auth/breakglass/ ./internal/auth/session/
./internal/api/handler/ ./internal/api/router/ ./cmd/server/
./internal/domain/auth/ — all pass.

CRIT-1..CRIT-5 + HIGH-1 + HIGH-2 of the 2026-05-10 audit now closed
on this branch. Spec at
cowork/auth-bundles-fixes-2026-05-10/06-high-1-2-revoke-and-rotate.md.

Refs: cowork/auth-bundles-audit-2026-05-10.md HIGH-1 HIGH-2

internal/auth/session/service_test.go

@@ -67,6 +67,19 @@ func (r *stubSessionRepo) Get(_ context.Context, id string) (*sessiondomain.Sess
 	return &clone, nil
 }
 
+func (r *stubSessionRepo) ListByActor(_ context.Context, actorID, actorType, _ string) ([]*sessiondomain.Session, error) {
+	r.mu.Lock()
+	defer r.mu.Unlock()
+	var out []*sessiondomain.Session
+	for _, row := range r.rows {
+		if row.ActorID == actorID && row.ActorType == actorType {
+			clone := *row
+			out = append(out, &clone)
+		}
+	}
+	return out, nil
+}
+
 func (r *stubSessionRepo) UpdateLastSeen(_ context.Context, id string) error {
 	r.mu.Lock()
 	defer r.mu.Unlock()