fix: stray "0" shown for steps with no timer (v0.52.1)

`{step.timerSeconds && (...)}` renders the literal 0 when timerSeconds is
the number 0 rather than null/undefined — only false/null/undefined skip
rendering in JSX, a bare falsy number doesn't. Some steps ended up with
timerSeconds stored as 0 instead of null (e.g. AI generation filling in a
"default" value for an optional field rather than omitting it), which
this guard then rendered as a bare "0" instead of hiding the timer.

Fixed at all 4 render sites (recipe page, cook mode, both print views) by
coercing to a real boolean (`!!step.timerSeconds`) — makes a stored 0
behave identically to null everywhere it's displayed.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

apps/web/lib/changelog.ts

@@ -1,5 +1,5 @@
 // Mirrors CHANGELOG.md at the repo root — update both together.
-export const APP_VERSION = "0.52.0";
+export const APP_VERSION = "0.52.1";
 
 export type ChangelogEntry = {
   version: string;
@@ -11,6 +11,13 @@ export type ChangelogEntry = {
 };
 
 export const CHANGELOG: ChangelogEntry[] = [
+  {
+    version: "0.52.1",
+    date: "2026-07-19 14:10",
+    fixed: [
+      "Steps with no timer sometimes showed a stray \"0\" on the recipe page, cook mode, and print views — a step whose timer happened to be stored as 0 (rather than empty) hit a JS truthiness quirk where `0 && ...` renders the literal 0 instead of nothing.",
+    ],
+  },
   {
     version: "0.52.0",
     date: "2026-07-19 13:55",