style: remove every em-dash and en-dash

Eighteen occurrences across fourteen files. Each sentence was repunctuated to
suit what the dash was doing rather than swapped for a hyphen, which produces
comma splices. The minus sign in folio-web's ledger is a minus sign and stays.

Claude-Session: https://claude.ai/code/session_01A5KmftdEJ49A9z5mF5ESrX

internal/trace/writer.go

@@ -92,7 +92,7 @@ type Action struct {
 	// LLMChoice is the 1-based number the model picked from the candidate list;
 	// LLMChosenAction is the action description it echoed for that number. The
 	// runner strict-skips when the echo disagrees with the numbered entry, so on
-	// a recorded action the two always agree — the replay UI shows them to
+	// a recorded action the two always agree; the replay UI shows them to
 	// confirm the reasoning matched the executed action.
 	LLMChoice       int    `json:"llm_choice,omitempty"`
 	LLMChosenAction string `json:"llm_chosen_action,omitempty"`