fix(desktop): keep statusctl quiet when the mode file is absent

read_mode() failed on a missing mode file with a shell redirection
error, 'statusctl: line 56: .../status.dnd: No such file or directory',
printed to stderr on every get/toggle before the file existed and
polluting waybar's exec stderr.

The '2>/dev/null' sat on the 'tr' command, but the error is the parent
shell's input redirection failure, which that redirect cannot suppress.
Guard on '[[ -e "$file" ]]' before reading; a missing file still
reads as 0, which was always the contract.

Mirror the fix into the plan so plan and script agree.

1 files changed, 6 insertions, 6 deletions

diff --git a/docs/superpowers/plans/2026-09-15-status-registry.md b/docs/superpowers/plans/2026-09-15-status-registry.md
index 5f86de4..614952c 100644
--- a/docs/superpowers/plans/2026-09-15-status-registry.md
+++ b/docs/superpowers/plans/2026-09-15-status-registry.md
@@ -390,12 +390,12 @@ esac
 file="$DIR/status.$mode"
 
 read_mode() {
-    local v
-    # An unreadable file reads as off, deliberately: a missing mode file is
-    # the normal state before anything has written one, and the redirect
-    # makes that fallback explicit rather than a side effect of a pipeline
-    # swallowing cat's exit status.
-    v="$(tr -d '[:space:]' < "$file" 2>/dev/null)"
+    local v=""
+    # A missing file is the normal state before anything has written one and
+    # reads as off. Guarding on existence keeps the shell's redirection error
+    # off stderr: `2>/dev/null` on the command cannot suppress a failure of
+    # its own input redirect.
+    [[ -e "$file" ]] && v="$(tr -d '[:space:]' < "$file" 2>/dev/null)"
     [[ "$v" == "1" ]] && printf '1' || printf '0'
 }