feat(tui): QA fixes + approval Ctrl keys, workflow focus, session UUID

- gate session-list nav on idle so in-session arrows/jk don't move the list (5a)
- approval dismiss on esc + in-session 'a' reopens a pending approval (5b)
- auto-focus a newly started workflow session (was running invisibly)
- approval actions on Ctrl chords (^a/^r/^x) matching the modal; bare/Alt letters no longer approve; diff closes on ^x/esc
- steer hint in the approval modal; session UUID in the input bar
- env-gated debug logging (CORREX_TUI_LOG) with k.Alt in the key trace

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

@@ -0,0 +1,47 @@
+package app
+
+import "log"
+
+// debugLog is a no-op unless EnableDebugLog is called from main (when the
+// CORREX_TUI_LOG env var is set). Tracing must never write to stderr while the
+// alt-screen is active, so it is routed through the standard logger which main
+// points at a file via tea.LogToFile.
+var debugLog = func(string, ...any) {}
+
+// EnableDebugLog switches tracing on, sending it through the standard logger.
+func EnableDebugLog() { debugLog = log.Printf }
+
+func (d DisplayState) String() string {
+	switch d {
+	case StateIdle:
+		return "Idle"
+	case StateInSession:
+		return "InSession"
+	case StateApproval:
+		return "Approval"
+	default:
+		return "?"
+	}
+}
+
+func (i InputMode) String() string {
+	switch i {
+	case ModeRouter:
+		return "Router"
+	case ModeFilter:
+		return "Filter"
+	default:
+		return "?"
+	}
+}
+
+func (e EditMode) String() string {
+	switch e {
+	case ModeNormal:
+		return "Normal"
+	case ModeInsert:
+		return "Insert"
+	default:
+		return "?"
+	}
+}