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/SettingsDrawer.svelte

@@ -7,7 +7,21 @@
   let { open, onClose }: Props = $props();
 
   // Local settings state (demo — no persistence in prototype)
-  let theme = $state('Catppuccin Mocha');
+  const THEMES = [
+    { id: 'mocha',      label: 'Catppuccin Mocha'     },
+    { id: 'macchiato',  label: 'Catppuccin Macchiato'  },
+    { id: 'frappe',     label: 'Catppuccin Frappé'     },
+    { id: 'latte',      label: 'Catppuccin Latte'      },
+  ];
+  let themeId = $state('mocha');
+  let themeDropdownOpen = $state(false);
+  let selectedThemeLabel = $derived(THEMES.find(t => t.id === themeId)?.label ?? 'Catppuccin Mocha');
+
+  function selectTheme(id: string) {
+    themeId = id;
+    themeDropdownOpen = false;
+  }
+
   let uiFontSize = $state(14);
   let termFontSize = $state(13);
 
@@ -60,8 +74,36 @@
           <h3 class="section-heading">Appearance</h3>
 
           <div class="setting-row">
-            <label class="setting-label" for="theme-select">Theme</label>
-            <div class="setting-value theme-pill">{theme}</div>
+            <label class="setting-label" for="theme-dropdown-btn">Theme</label>
+            <div class="theme-dropdown">
+              <button
+                id="theme-dropdown-btn"
+                class="theme-dropdown-btn"
+                onclick={() => themeDropdownOpen = !themeDropdownOpen}
+                aria-haspopup="listbox"
+                aria-expanded={themeDropdownOpen}
+              >
+                <span class="theme-dropdown-label">{selectedThemeLabel}</span>
+                <svg class="theme-chevron" class:open={themeDropdownOpen} viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="2" aria-hidden="true">
+                  <polyline points="6 9 12 15 18 9"/>
+                </svg>
+              </button>
+              {#if themeDropdownOpen}
+                <ul class="theme-dropdown-list" role="listbox" aria-label="Theme options">
+                  {#each THEMES as t}
+                    <li
+                      class="theme-option"
+                      class:selected={themeId === t.id}
+                      role="option"
+                      aria-selected={themeId === t.id}
+                      onclick={() => selectTheme(t.id)}
+                      onkeydown={(e) => (e.key === 'Enter' || e.key === ' ') && selectTheme(t.id)}
+                      tabindex="0"
+                    >{t.label}</li>
+                  {/each}
+                </ul>
+              {/if}
+            </div>
           </div>
 
           <div class="setting-row">
@@ -232,17 +274,76 @@
     color: var(--ctp-subtext1);
   }
 
-  .setting-value {
-    font-size: 0.8125rem;
-    color: var(--ctp-text);
+  /* Theme dropdown */
+  .theme-dropdown {
+    position: relative;
   }
 
-  .theme-pill {
+  .theme-dropdown-btn {
+    display: flex;
+    align-items: center;
+    gap: 0.375rem;
     background: var(--ctp-surface0);
-    padding: 0.2rem 0.5rem;
+    border: 1px solid var(--ctp-surface1);
     border-radius: 0.3rem;
-    font-size: 0.75rem;
+    padding: 0.2rem 0.5rem;
     color: var(--ctp-mauve);
+    font-family: var(--ui-font-family);
+    font-size: 0.75rem;
+    cursor: pointer;
+    transition: border-color 0.12s;
+    white-space: nowrap;
+  }
+
+  .theme-dropdown-btn:hover { border-color: var(--ctp-surface2); }
+
+  .theme-dropdown-label { flex: 1; }
+
+  .theme-chevron {
+    width: 0.75rem;
+    height: 0.75rem;
+    color: var(--ctp-overlay1);
+    transition: transform 0.15s;
+    flex-shrink: 0;
+  }
+
+  .theme-chevron.open { transform: rotate(180deg); }
+
+  .theme-dropdown-list {
+    position: absolute;
+    right: 0;
+    top: calc(100% + 0.25rem);
+    z-index: 10;
+    list-style: none;
+    margin: 0;
+    padding: 0.25rem;
+    background: var(--ctp-mantle);
+    border: 1px solid var(--ctp-surface1);
+    border-radius: 0.375rem;
+    min-width: 11rem;
+    box-shadow: 0 0.5rem 1.25rem color-mix(in srgb, var(--ctp-crust) 60%, transparent);
+    display: flex;
+    flex-direction: column;
+    gap: 0.0625rem;
+  }
+
+  .theme-option {
+    padding: 0.35rem 0.5rem;
+    border-radius: 0.25rem;
+    font-size: 0.8125rem;
+    color: var(--ctp-subtext1);
+    cursor: pointer;
+    transition: background 0.08s, color 0.08s;
+    outline: none;
+  }
+
+  .theme-option:hover,
+  .theme-option:focus { background: var(--ctp-surface0); color: var(--ctp-text); }
+
+  .theme-option.selected {
+    background: color-mix(in srgb, var(--ctp-mauve) 15%, transparent);
+    color: var(--ctp-mauve);
+    font-weight: 500;
   }
 
   /* Font stepper */