Aero goes underwater with rising bubbles; floating cookie notice; Czech title

Frutiger Aero, closer to the mock:
- The scene is water now: sun shafts through a bright surface, caustic
  patches, reeds on the left, a city silhouette on the right, and ten soap
  bubbles that actually rise (own keyframes, varied sizes/speeds/sway; the
  spans are display:none outside aero so they cost nothing elsewhere, and
  they sit still under reduced motion).
- Pale blue glass at 0.8: still reads as glass, but dark navy text clears
  4.5:1 over the water. The phone tab bar mixes the sheet glass instead of
  the page — in aero the page *is* the water, which left its labels at 3.9:1.
- The aero page-level text (muted/subtle) is much darker for the same reason.
- The PWA status bar follows the new water blue (#2fa7e6).

The cookie notice is floating glass now (blurred backdrop, rim, shadow): as a
plain card it read as part of the page background instead of a notice.

Czech: "Tvoje mraznička" -> "Tvůj mrazák" (library title), test updated.

Contrast: 0 below-minimum findings and 0 axe violations across every screen,
all three themes. Version 0.2.1, SW -> freezmo-v55.

tests/i18n-test.mjs

@@ -29,7 +29,7 @@ const browser = await launchBrowser();
   await seed(page, { locale: "cs", decks: [DECK] });
   await page.goto(BASE, { waitUntil: "networkidle" });
   await page.waitForTimeout(900);
-  check("library title is Czech", await page.getByRole("heading", { name: "Tvoje mraznička" }).isVisible());
+  check("library title is Czech", await page.getByRole("heading", { name: "Tvůj mrazák" }).isVisible());
   check("sidebar says Všechny sady", await page.getByRole("button", { name: /Všechny sady/ }).first().isVisible());
   check("sidebar says Nezařazené", await page.getByRole("button", { name: /Nezařazené/ }).first().isVisible());
   check("deck card CTA is Studovat", (await page.getByRole("link", { name: "Studovat" }).count()) === 1);