docs: document bookmarks panel in README, ARCHITECTURE, and website

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

ARCHITECTURE.md

@@ -161,6 +161,8 @@ A session is the working unit of the product. It binds together:
 
 This is how Aryx keeps "ongoing work" first class. Sessions can survive restarts, can be organized, and can accumulate operational history over time.
 
+Individual messages can be pinned as bookmarks. A dedicated bookmarks panel (`BookmarksPanel`) lists all pinned messages across all sessions globally, navigating to the originating session and message on selection. This data is derived renderer-side from the workspace state; there is no separate backend API.
+
 ### Runs
 
 Each user turn becomes a **run**. A run is more than the final assistant output; it also tracks:

README.md

@@ -43,6 +43,7 @@ Aryx is a desktop app that turns GitHub Copilot into a full workspace. Connect r
 | Session branching | Fork a session at any user message to explore a different direction |
 | Session search | Full-text search across all session messages, not just titles |
 | Message actions | Copy, pin, edit-and-resend, and regenerate individual messages |
+| Bookmarks | Browse all pinned messages across sessions in one panel (`Ctrl+Shift+B`) |
 | System tray | Minimize to tray, quick-launch scratchpads, and see running session count |
 | Desktop notifications | Native OS alerts when runs complete, fail, or need approval |
 | Onboarding | First-launch walkthrough, interactive tooltips, and a "try it" quickstart |

website/src/pages/index.astro

@@ -332,6 +332,16 @@ import Base from '../layouts/Base.astro';
               <p class="mt-0.5 text-xs leading-relaxed text-warm-400">Copy, pin, edit-and-resend, and regenerate individual messages.</p>
             </div>
           </div>
+          <!-- Bookmarks -->
+          <div class="group flex gap-3.5 rounded-xl px-3 py-2.5 transition hover:bg-card/60" data-reveal data-reveal-d="5">
+            <div class="mt-0.5 flex size-8 shrink-0 items-center justify-center rounded-lg bg-brand/[0.07] text-brand transition group-hover:bg-brand/[0.12]">
+              <svg class="size-3.5" fill="none" stroke="currentColor" viewBox="0 0 24 24"><path stroke-linecap="round" stroke-linejoin="round" stroke-width="2" d="M5 5a2 2 0 012-2h10a2 2 0 012 2v16l-7-3.5L5 21V5z"></path></svg>
+            </div>
+            <div>
+              <h4 class="text-sm font-medium text-warm-50">Bookmarks</h4>
+              <p class="mt-0.5 text-xs leading-relaxed text-warm-400">Browse all pinned messages across sessions in one panel via <kbd class="text-warm-200">Ctrl+Shift+B</kbd>.</p>
+            </div>
+          </div>
           <!-- System Tray -->
           <div class="group flex gap-3.5 rounded-xl px-3 py-2.5 transition hover:bg-card/60" data-reveal data-reveal-d="6">
             <div class="mt-0.5 flex size-8 shrink-0 items-center justify-center rounded-lg bg-brand/[0.07] text-brand transition group-hover:bg-brand/[0.12]">