refactor: rename inspect to replay across the codebase

Renames inspect-ui/ to replay-ui/, internal/inspect/ to internal/replay/,
the CLI subcommand from `sanderling inspect` to `sanderling replay`, and
updates all references in docs, Makefile, README, and Go comments.

internal/ltl/evaluator.go

@@ -265,7 +265,7 @@ func violated() reduceResult { return reduceResult{status: statusViolated} }
 
 // violatedWith reports a violation that originates at the given sub-formula
 // with the given reason. The reason distinguishes a thrown predicate from a
-// plain false so callers (and the inspect UI) can render the cause.
+// plain false so callers (and the replay UI) can render the cause.
 func violatedWith(formula Formula, reason string) reduceResult {
 	return reduceResult{
 		status:  statusViolated,

internal/ltl/formula.go

@@ -23,7 +23,7 @@ type PredicateLabel interface {
 // ErrorFormula represents a thunk that threw during evaluation. The verifier
 // substitutes one of these into the residual when MarshalJSON would otherwise
 // have to encode an opaque thunk that already errored. It exists so that the
-// inspect UI can render "predicate threw" inline.
+// replay UI can render "predicate threw" inline.
 type ErrorFormula struct {
 	Message string
 }