fix(pwa): keep the new worker's precache when loading a new version

The reload cleared every HealthLog cache after asking the worker to
update, but the update resolves as soon as the new worker starts
installing. Its fresh precache of logos and favicon was deleted with
the old ones, so the installed app lacked them offline. Leave the
target release's caches in place.

src/components/__tests__/version-poller.test.ts

@@ -15,7 +15,7 @@
 
 import { describe, expect, it } from "vitest";
 
-import { resolveVersionPollDecision } from "../version-poller";
+import { cachesToEvict, resolveVersionPollDecision } from "../version-poller";
 
 describe("resolveVersionPollDecision", () => {
   it("is up-to-date when live matches the shell", () => {
@@ -144,3 +144,31 @@ describe("evictAndReload", () => {
     ]);
   });
 });
+
+describe("cachesToEvict", () => {
+  const keys = [
+    "healthlog-static-v1.41.2",
+    "healthlog-pages-v1.41.2",
+    "healthlog-data-v1.41.2",
+    "healthlog-static-v1.42.0",
+    "another-app-cache",
+  ];
+
+  it("keeps the target release's caches the new worker just filled", () => {
+    expect(cachesToEvict(keys, "1.42.0")).toEqual([
+      "healthlog-static-v1.41.2",
+      "healthlog-pages-v1.41.2",
+      "healthlog-data-v1.41.2",
+    ]);
+  });
+
+  it("reads the target with or without its v", () => {
+    expect(cachesToEvict(keys, "v1.42.0")).not.toContain(
+      "healthlog-static-v1.42.0",
+    );
+  });
+
+  it("never touches another app's caches", () => {
+    expect(cachesToEvict(keys, "1.43.0")).not.toContain("another-app-cache");
+  });
+});