feat(api): let in-game staff manage any server without claiming it

The web face has always granted staff the run of the fleet (isOwnerOrAdmin
passes an admin for stop/command/console/access on any node), but the
internal face explicitly had "no admin tier": a linked administrator in game
could only wake servers they owned or that autostartPolicy permitted. The
only way to manage another player's (or an unclaimed) server from inside the
game was to claim it — seizing ownership and burning the admin's own quota.

Give authorizeWakeByUUID the admin tier on the same trust anchor the op-login
approve already uses: verified online-mode UUID -> account link -> stored
role. A linked staff member now wakes ANY node under any policy (so
`/felis go` works fleet-wide without claiming); the owner bypass and the
policy gates are unchanged, and an unlinked UUID still fails safe.

Centralize the staff-role rule while at it: staffRole(role) in auth.go
(admin, plus owner as its superset) now backs Principal.IsAdmin, the session
ViaAdminAccess grading, the op-login approve gate and the new wake tier.
That also fixes a real hole in the approve gate, which required role=admin
exactly: an Owner manually promoted to role='owner' per migration 0011's
upgrade note would have been refused by their own in-game approval door.

The lobby menu still renders "Claim & Start" on ownerless tiles — claiming
becomes optional for staff rather than the only entry — so the velocity
plugin needs no change.

internal/api/session.go

@@ -159,7 +159,7 @@ func (s SessionAuth) Authenticate(r *http.Request) (*Principal, error) {
 		UserID:         u.ID,
 		Email:          u.Email,
 		Role:           u.Role,
-		ViaAdminAccess: (u.Role == "admin" || u.Role == "owner") && hostIsAdminConsole(r, s.RootDomain, s.AdminHostname),
+		ViaAdminAccess: staffRole(u.Role) && hostIsAdminConsole(r, s.RootDomain, s.AdminHostname),
 		EmailVerified:  u.EmailVerified,
 		ViaSession:     true,
 	}, nil