Add MASS4.Graph.State: cycles, typed triggers and per-instance state #15

Current State

State machines built on string states and magic-string event names fail silently when a name is misspelled or renamed. States and transitions are cyclic by nature, and each running instance needs its own current state and timers.

Tasks:

• States and transitions on top of the core model; cycles and self-transitions allowed
• Triggers as registered typed identities, resolved at registration or compile time, never by string
• Per-instance current state and timers declared through the instance layout contract
• Transition guards evaluated through Dataflow
• Replace the hand-written stand-in in the core zero-allocation regression test with a real State graph

Acceptance Criteria:

• Referencing an unknown trigger or state is a build- or load-time diagnostic, not a runtime miss
• 1000 instances of one asset tick with zero per-tick allocations
• Depends only on MASS4.Graph

Related:

• Epic: semantics triad — Dataflow, Control and State #2 (semantics epic), Add blackboard, subgraph, instance and evaluation contracts #10 (zero-allocation regression test), Prove semantics composition with a mixed State × Dataflow document #16, Add the FSM contract sample: one asset, 1000 instances #22 (FSM sample)