Model match-clock actions: Pause/Unpause Match Time, Set Match Time, Set Slow Motion #120

Problem

After #118, Bastion on the committed docs/scenario-examples/valid/bastion.json runs 63 ticks and stops:

not_modeled — action pauseMatchTime, tick 63, rule 187 [Bastion] Freeze match time, no event player, action 8.

The same rule continues with Set Slow Motion, Unpause Match Time, Set Match Time.

Scope

Model the match-clock actions as one family:

• Pause Match Time, Unpause Match Time, Set Match Time, Set Slow Motion, and the readers they change (Match Time Remaining/Total Time Elapsed/Is Game In Progress style values, whichever the catalog defines).
• Clock state is part of the world: a paused clock stops advancing Total Time Elapsed / match time; slow motion scales the speed factor. Writes appear in the trace changes.
• Do not guess scheduler consequences. If slow motion changes how Wait durations map to ticks and no capture measures it, record the factor and keep Wait timing unchanged only if a finding in docs/findings.md says so; otherwise a Wait while a non-100 slow-motion factor is active ends not_modeled naming the construct.
• Anything unanswerable stays not_modeled; no hidden defaults.

Acceptance

• Bastion advances past rule 187; the next stop (or completion) is recorded in the PR body from a real rerun.
• Trace changes show pause/unpause, match-time set and slow-motion factor.
• Tests for each action, each reader, and the Wait-under-slow-motion stop.
• Docs updated; size guards respected.