feat(offline): redesign sync UI and PWA polish

Split the single OfflineSyncButton into two surfaces with distinct
intents:
  - OfflineSyncBanner: dismissable promo on the recipe index that
    encourages first-time download (only when standalone + not yet
    synced).
  - OfflineSyncIndicator: small status pip overlaid on the nav logo
    when offline data is available, opening a popover with sync /
    clear actions.

Also fold the sync / clear actions into the UserHeader options menu so
the avatar dropdown is the canonical place to manage offline data.
Header.svelte gains a `logo_overlay` snippet slot to host the
indicator pip.

Other:
  - manifest.json: prefer the theme-aware SVG as the primary install
    icon and drop the redundant 512px raster (kept maskable 192px).
  - scripts/deploy.sh: build locally and rsync artifacts to the
    server, avoiding any pnpm/git work on the production host.

Bump 1.57.8 -> 1.58.0.

package.json

@@ -1,6 +1,6 @@
 {
 	"name": "homepage",
-	"version": "1.57.8",
+	"version": "1.58.0",
 	"private": true,
 	"type": "module",
 	"scripts": {