feat(electrobun): fixes + 7 new features (terminal input, file browser, memory, toasts)

Fixes:
- Terminal accepts keyboard input (echo mode with prompt)
- Terminal drawer collapses properly (display:none preserves xterm state)

Features:
- 6 project tabs: Model | Docs | Context | Files | SSH | Memory
- FileBrowser.svelte: recursive tree with expand/collapse + file preview
- MemoryTab.svelte: memory cards with trust badges (human/agent/auto)
- Subagent tree in AgentPane (demo: search-agent, test-runner)
- Drag resize handle between agent pane and terminal
- Theme dropdown in Settings (4 Catppuccin flavors)
- ToastContainer.svelte: auto-dismiss notifications

ui-electrobun/src/mainview/TerminalTabs.svelte

@@ -38,11 +38,9 @@
     const idx = tabs.findIndex(t => t.id === id);
     tabs = tabs.filter(t => t.id !== id);
     if (activeTabId === id) {
-      // activate neighbor
       const next = tabs[Math.min(idx, tabs.length - 1)];
       activeTabId = next?.id ?? '';
     }
-    // Remove from mounted to free resources
     const m = new Set(mounted);
     m.delete(id);
     mounted = m;
@@ -50,7 +48,6 @@
 
   function activateTab(id: string) {
     activeTabId = id;
-    // Mount on first activation
     if (!mounted.has(id)) {
       mounted = new Set([...mounted, id]);
     }
@@ -120,23 +117,24 @@
     </div>
   </div>
 
-  <!-- Terminal panes: display:flex/none to preserve xterm state -->
-  {#if !collapsed}
-    <div class="term-panes">
-      {#each tabs as tab (tab.id)}
-        {#if mounted.has(tab.id)}
-          <div
-            class="term-pane"
-            style:display={activeTabId === tab.id ? 'flex' : 'none'}
-            role="tabpanel"
-            aria-label={tab.title}
-          >
-            <Terminal />
-          </div>
-        {/if}
-      {/each}
-    </div>
-  {/if}
+  <!--
+    Terminal panes: always rendered (display:none when collapsed) so xterm state
+    is preserved across collapse/expand. Using display:none instead of {#if}.
+  -->
+  <div class="term-panes" style:display={collapsed ? 'none' : 'block'}>
+    {#each tabs as tab (tab.id)}
+      {#if mounted.has(tab.id)}
+        <div
+          class="term-pane"
+          style:display={activeTabId === tab.id ? 'flex' : 'none'}
+          role="tabpanel"
+          aria-label={tab.title}
+        >
+          <Terminal />
+        </div>
+      {/if}
+    {/each}
+  </div>
 </div>
 
 <style>