Consolidate Boundaries + History under the account; sectioned /account

The inline Boundaries/History panels lived on the home page, so opening them while
scrolled left you stranded. Move everything "yours" behind the account icon:

- Home header slims to: Saved (opens a right-side flyout, signed-in) · shield
  (Boundaries indicator — filled when active — linking to the Boundaries section) ·
  avatar. The inline panels + the home "saved" view are gone.
- /account is now a sectioned hub (left sidebar on desktop, top tabs on mobile),
  OPEN TO EVERYONE with each section self-gating: Profile (sign-in), Saved (sign-in),
  History (device/account), Boundaries (device/account), Admin (admins). This keeps
  Boundaries/History usable without an account (they're device-local) while
  consolidating the UI — and every section loads at the top, fixing the scroll bug.
- Lift Calm Filters and History into shared stores (prefs.svelte.js, history.svelte.js)
  so the home feed (applies/records) and the account page (edits/manages) share one
  source of truth. New SavedFlyout component. Card boundary actions only render when a
  handler is provided.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

frontend/src/lib/components/ArticleCard.svelte

@@ -155,9 +155,9 @@
           </div>
         {/if}
       </span>
-      {#if article.topic}<button class="mute" onclick={() => act('notToday', article.topic)}>Not today</button>{/if}
-      {#if article.flavor}<button class="mute" onclick={() => act('lessLikeThis', article.flavor)}>Less like this</button>{/if}
-      {#if article.topic}<button class="mute" onclick={() => act('alwaysHide', article.topic)}>Hide {article.topic}</button>{/if}
+      {#if onaction && article.topic}<button class="mute" onclick={() => act('notToday', article.topic)}>Not today</button>{/if}
+      {#if onaction && article.flavor}<button class="mute" onclick={() => act('lessLikeThis', article.flavor)}>Less like this</button>{/if}
+      {#if onaction && article.topic}<button class="mute" onclick={() => act('alwaysHide', article.topic)}>Hide {article.topic}</button>{/if}
     </div>
   </div>
 </article>