feat(recovery,context): tier-2 intent-holder arbiter + remaining-delta pinning + surfaced signal events

- recovery: two-tier repair ladder — owner then arbiter (recovery stage recast
  as intent-holder, holds initial intent, reconciles cross-file contract disputes)
  with independent INTENT_ROUTE_BUDGET; RecoveryRoutingTest coverage
- context: remaining-delta checklist pinning (RemainingDelta{Pinning,Entry}Test)
- surface write-only events (session name, quality signals) into stats/browse
- parseToolArguments lenient-Json fallback for bare-key drift
- tools: ChildProcess seam

apps/tui-go/internal/app/prefs.go

@@ -11,6 +11,7 @@ import (
 type prefs struct {
 	StatusbarHidden     []string `json:"statusbarHidden"`
 	InlineActionsHidden bool     `json:"inlineActionsHidden"`
+	ThinkingShown       bool     `json:"thinkingShown"`
 }
 
 // statusSegment is one toggleable status-bar segment. The always-on segments (correx label,
@@ -97,3 +98,10 @@ func saveInlineActionsHidden(hidden bool) {
 	p.InlineActionsHidden = hidden
 	savePrefs(p)
 }
+
+// saveThinkingShown persists the reasoning-blocks toggle, preserving other prefs fields.
+func saveThinkingShown(shown bool) {
+	p := loadPrefs()
+	p.ThinkingShown = shown
+	savePrefs(p)
+}