Issue #3609678: Never cache the process-instance monitoring page (token state changes via raw DB updates bypass cache tags)

Implements #3609678.

The process-instance monitoring page rendered stale token state (a token shown parked on a step the run had already left) until a manual cache clear.

Root cause: token status transitions are raw database updates (the engine's atomic PARKED/ACTIVE/CONSUMED claims), which never invalidate an entity or list cache tag. The signal() claim in WorkflowExecutor did a bare UPDATE, so it left the token's entity cache stale, and the tag-cached trace page could not see the change.

• WorkflowExecutor::signal() now claims the token through the shared StatusTransitions helper, which resets the token's entity cache and invalidates its tags (entity + list) on the flip, so any entity-API consumer and any tag-cached render see the real state.
• OrchestraUiController::instance() (the monitoring page) additionally declares #cache max-age 0: a live operational view must always reflect the real state, belt-and-suspenders against any raw-update path that still bypasses tags.

Kernel test asserts the instance page declares max-age 0; the existing signal/resume engine tests cover the transition behaviour.