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/ToastContainer.svelte

@@ -0,0 +1,132 @@
+<script lang="ts">
+  type ToastVariant = 'success' | 'warning' | 'error' | 'info';
+
+  interface Toast {
+    id: number;
+    message: string;
+    variant: ToastVariant;
+    dismissAt: number; // epoch ms
+  }
+
+  let toasts = $state<Toast[]>([]);
+  let counter = $state(0);
+
+  // Public API — call via component binding or module-level store
+  export function addToast(message: string, variant: ToastVariant = 'info', durationMs = 4000) {
+    const id = ++counter;
+    toasts = [...toasts, { id, message, variant, dismissAt: Date.now() + durationMs }];
+    setTimeout(() => dismiss(id), durationMs);
+  }
+
+  function dismiss(id: number) {
+    toasts = toasts.filter(t => t.id !== id);
+  }
+
+  // Show a demo toast on mount
+  import { onMount } from 'svelte';
+  onMount(() => {
+    setTimeout(() => {
+      addToast('Agent Orchestrator connected', 'success', 4000);
+    }, 800);
+  });
+
+  const ICONS: Record<ToastVariant, string> = {
+    success: '✓',
+    warning: '⚠',
+    error:   '✕',
+    info:    'ℹ',
+  };
+</script>
+
+<div class="toast-container" aria-live="polite" aria-label="Notifications">
+  {#each toasts as toast (toast.id)}
+    <div class="toast toast-{toast.variant}" role="alert">
+      <span class="toast-icon" aria-hidden="true">{ICONS[toast.variant]}</span>
+      <span class="toast-msg">{toast.message}</span>
+      <button
+        class="toast-close"
+        onclick={() => dismiss(toast.id)}
+        aria-label="Dismiss notification"
+      >×</button>
+    </div>
+  {/each}
+</div>
+
+<style>
+  .toast-container {
+    position: fixed;
+    bottom: 2.5rem; /* above status bar */
+    right: 0.875rem;
+    z-index: 400;
+    display: flex;
+    flex-direction: column;
+    gap: 0.375rem;
+    pointer-events: none;
+  }
+
+  .toast {
+    display: flex;
+    align-items: center;
+    gap: 0.5rem;
+    padding: 0.5rem 0.625rem;
+    border-radius: 0.4375rem;
+    border: 1px solid var(--ctp-surface1);
+    background: var(--ctp-mantle);
+    font-size: 0.8125rem;
+    color: var(--ctp-text);
+    pointer-events: auto;
+    animation: toast-in 0.18s ease-out;
+    min-width: 14rem;
+    max-width: 22rem;
+    box-shadow: 0 0.5rem 1.5rem color-mix(in srgb, var(--ctp-crust) 70%, transparent);
+  }
+
+  @keyframes toast-in {
+    from { transform: translateX(1.5rem); opacity: 0; }
+    to   { transform: translateX(0);      opacity: 1; }
+  }
+
+  .toast-success { border-left: 3px solid var(--ctp-green); }
+  .toast-warning { border-left: 3px solid var(--ctp-yellow); }
+  .toast-error   { border-left: 3px solid var(--ctp-red); }
+  .toast-info    { border-left: 3px solid var(--ctp-blue); }
+
+  .toast-icon {
+    flex-shrink: 0;
+    font-size: 0.75rem;
+    font-weight: 700;
+  }
+
+  .toast-success .toast-icon { color: var(--ctp-green); }
+  .toast-warning .toast-icon { color: var(--ctp-yellow); }
+  .toast-error   .toast-icon { color: var(--ctp-red); }
+  .toast-info    .toast-icon { color: var(--ctp-blue); }
+
+  .toast-msg {
+    flex: 1;
+    line-height: 1.4;
+  }
+
+  .toast-close {
+    flex-shrink: 0;
+    width: 1.25rem;
+    height: 1.25rem;
+    background: transparent;
+    border: none;
+    color: var(--ctp-overlay1);
+    font-size: 1rem;
+    cursor: pointer;
+    display: flex;
+    align-items: center;
+    justify-content: center;
+    border-radius: 0.2rem;
+    padding: 0;
+    transition: color 0.1s, background 0.1s;
+    line-height: 1;
+  }
+
+  .toast-close:hover {
+    color: var(--ctp-text);
+    background: var(--ctp-surface0);
+  }
+</style>