relay UI overhaul, favicon, settings, admin last-seen, fixes

Relay:
  - Inbox/shared/sent split into own view-inbox (nav button + poll).
    Compose is now single-column, centered.
  - Header logo links to compose. Inbox badge stays fresh on all
    views via a quiet loadInbox on every view switch.
  - Mobile menu: full-height sheet below header, larger buttons
    (15px font, 14px padding), full width.
  - Login form wrapped in <form> with name attributes + for/id on
    labels so password managers can autofill.
  - Admin user list shows "last seen <relative time>" per user.
    last_seen_at column on tenants, updated on every authenticated
    request (session + client API).
  - Cache-busting on style.css + app.js via filemtime.
  - View persistence in localStorage (survives reload).
  - Shared-bucket cards show title only (preview line removed).

Favicon:
  - favicon.svg added to project root + copied to public/, relay/,
    website/. Linked via <link rel="icon" type="image/svg+xml"> in
    all three <head> sections.

Settings:
  - New toggle: "Show shopping list items in task collector"
    (default off). collectTasks skips #einkauf/#shopping cards when
    disabled.

Fixes:
  - card-spinner gets display:inline-block so it rotates outside
    flex containers (shopping save spinner).
  - Tim tab test opens the plugin before checking active state.
  - Compose view centered with margin:auto on desktop.

Bumps to 1.9.29.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

public/index.php

@@ -1159,6 +1159,7 @@ if (str_starts_with($route, '/api/')) {
     <meta charset="UTF-8">
     <meta name="viewport" content="width=device-width, initial-scale=1.0">
     <title>hyprcrd</title>
+    <link rel="icon" type="image/svg+xml" href="favicon.svg">
     <link rel="stylesheet" href="css/fonts.css">
     <link rel="stylesheet" href="css/vendor/phosphor-regular.css">
     <link rel="stylesheet" href="css/vendor/phosphor-fill.css">
@@ -1927,6 +1928,7 @@ if (str_starts_with($route, '/api/')) {
                                 <div class="toggle-row" data-toggle="setting-confirm-delete"><span class="toggle-label">Confirm before delete</span><div class="toggle-switch" id="setting-confirm-delete"></div></div>
                                 <div class="toggle-row" data-toggle="setting-auto-save"><span class="toggle-label">Auto-save on close (editor)</span><div class="toggle-switch" id="setting-auto-save"></div></div>
                                 <div class="toggle-row" data-toggle="setting-open-switches-bucket"><span class="toggle-label">Switch to card's bucket on open (search / link)</span><div class="toggle-switch" id="setting-open-switches-bucket"></div></div>
+                                <div class="toggle-row" data-toggle="setting-tasks-show-shopping"><span class="toggle-label">Show shopping list items in task collector</span><div class="toggle-switch" id="setting-tasks-show-shopping"></div></div>
                             </div>
                         </div>
                     </div>