refactor(dashboard): extract modular Preact component structure

Replace the monolithic single-file dashboards (dashboard.html,
dashboard-preact.html) with a proper modular directory structure:

  dashboard/
    index.html              - Entry point, loads main.js
    main.js                 - App bootstrap, mounts <App> to #root
    styles.css              - Global styles (dark theme, typography)
    components/
      App.js                - Root component, state management, polling
      Header.js             - Top bar with refresh/timing info
      Sidebar.js            - Project tree navigation
      SessionCard.js        - Individual session card with status/actions
      SessionGroup.js       - Group sessions by project path
      Modal.js              - Full conversation viewer overlay
      ChatMessages.js       - Message list with role styling
      MessageBubble.js      - Individual message with markdown
      QuestionBlock.js      - User question input with quick options
      EmptyState.js         - "No sessions" placeholder
      OptionButton.js       - Quick response button component
      SimpleInput.js        - Text input with send button
    lib/
      preact.js             - Preact + htm ESM bundle (CDN shim)
      markdown.js           - Lightweight markdown-to-HTML renderer
    utils/
      api.js                - fetch wrappers for /api/* endpoints
      formatting.js         - Time formatting, truncation helpers
      status.js             - Session status logic, action availability

This structure enables:
- Browser-native ES modules (no build step required)
- Component reuse and isolation
- Easier styling and theming
- IDE support for component navigation

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

dashboard/components/SimpleInput.js

@@ -0,0 +1,49 @@
+import { html, useState } from '../lib/preact.js';
+import { getStatusMeta } from '../utils/status.js';
+
+export function SimpleInput({ sessionId, status, onRespond }) {
+  const [text, setText] = useState('');
+  const [focused, setFocused] = useState(false);
+  const meta = getStatusMeta(status);
+
+  const handleSubmit = (e) => {
+    e.preventDefault();
+    e.stopPropagation();
+    if (text.trim()) {
+      onRespond(sessionId, text.trim(), true, 0);
+      setText('');
+    }
+  };
+
+  return html`
+    <form onSubmit=${handleSubmit} class="flex items-end gap-2.5" onClick=${(e) => e.stopPropagation()}>
+      <textarea
+        value=${text}
+        onInput=${(e) => {
+          setText(e.target.value);
+          e.target.style.height = 'auto';
+          e.target.style.height = e.target.scrollHeight + 'px';
+        }}
+        onKeyDown=${(e) => {
+          if (e.key === 'Enter' && !e.shiftKey) {
+            e.preventDefault();
+            handleSubmit(e);
+          }
+        }}
+        onFocus=${() => setFocused(true)}
+        onBlur=${() => setFocused(false)}
+        placeholder="Send a message..."
+        rows="1"
+        class="flex-1 resize-none overflow-hidden rounded-xl border border-selection/75 bg-bg/70 px-3 py-2 text-sm text-fg placeholder:text-dim focus:outline-none"
+        style=${{ minHeight: '38px', maxHeight: '150px', borderColor: focused ? meta.borderColor : undefined }}
+      />
+      <button
+        type="submit"
+        class="shrink-0 rounded-xl px-3 py-2 text-sm font-medium transition-all hover:-translate-y-0.5 hover:brightness-110"
+        style=${{ backgroundColor: meta.borderColor, color: '#0a0f18' }}
+      >
+        Send
+      </button>
+    </form>
+  `;
+}