feat(sidebar): daily-notes panel + Q&A deep-link to file offset

Daily notes panel:
- src/sidebar/daily-notes-panel.js — new sidebar panel that lists every
  YYYY-MM-DD.md in the daily-notes dir (newest first), with a Today
  button that creates/opens today's entry. Refresh button reloads.
  Clicking a row calls onOpenFile(path). DOM is built with textContent
  for dynamic fields — no XSS surface from a hostile filename.
- src/main.js — daily-notes:list IPC now returns absolute paths (joined
  with the daily-notes dir) so the renderer can pass them straight to
  open-file-path without re-synthesizing.
- src/renderer.js — registers the panel; icon for the daily-notes
  button (calendar icon).
- src/index.html — calendar SVG icon for the daily-notes sidebar entry.

Q&A deep-link:
- src/main.js — open-file-path accepts either a string (legacy) or an
  object {path, offset}. The offset is forwarded to the renderer via
  file-opened.
- src/renderer.js — file-opened handler scrolls the editor to the
  offset using EditorView.scrollIntoView(y: 'center') so the matching
  passage lands in the middle of the visible area.
- search panel now passes {path, offset} to open-file-path so Q&A
  results with chunk offsets jump straight to the passage.

Tests (12 new, tests/daily-notes-panel.test.js):
  - mount, empty state, list rendering
  - Today button → onOpenFile, 'Created today' / 'Today already exists' status
  - error paths (openToday reject, listExisting reject, listExisting missing)
  - click + Enter/Space on a row open the right path
  - refresh() re-fetches, keeps status when keepStatus:true
  - non-md entries filtered out
  - XSS-safe textContent for dynamic data

Full suite: 73 suites, 873 tests, lint+format clean.

Amit Haridas

tests/daily-notes-panel.test.js

@@ -0,0 +1,175 @@
+/**
+ * @jest-environment jsdom
+ *
+ * Daily notes sidebar panel tests.
+ */
+const { renderDailyNotesPanel } = require('../src/sidebar/daily-notes-panel');
+
+function mountPanel(deps = {}) {
+  const container = document.createElement('div');
+  document.body.appendChild(container);
+  const api = renderDailyNotesPanel(container, {
+    openToday: deps.openToday || jest.fn().mockResolvedValue({ path: '/notes/2026-09-14.md', created: true }),
+    listExisting: deps.listExisting || jest.fn().mockResolvedValue([]),
+    onOpenFile: deps.onOpenFile || jest.fn(),
+    ...deps,
+  });
+  return { container, api };
+}
+
+async function flush() {
+  for (let i = 0; i < 5; i++) await Promise.resolve();
+}
+
+describe('renderDailyNotesPanel — mounting', () => {
+  test('mounts the panel structure', () => {
+    const { container } = mountPanel();
+    expect(container.querySelector('.daily-notes-panel')).not.toBeNull();
+    expect(container.querySelector('#daily-notes-today')).not.toBeNull();
+    expect(container.querySelector('#daily-notes-refresh')).not.toBeNull();
+    expect(container.querySelector('#daily-notes-list')).not.toBeNull();
+  });
+
+  test('shows the empty-state message when there are no notes', async () => {
+    const { container } = mountPanel({ listExisting: jest.fn().mockResolvedValue([]) });
+    await flush();
+    expect(container.querySelector('.daily-notes-empty')).not.toBeNull();
+    expect(container.textContent).toMatch(/Press.*Today/);
+  });
+
+  test('renders one row per filename', async () => {
+    const { container } = mountPanel({
+      listExisting: jest.fn().mockResolvedValue([
+        '/notes/daily/2026-09-14.md',
+        '/notes/daily/2026-09-13.md',
+        '/notes/daily/2026-09-10.md',
+      ]),
+    });
+    await flush();
+    const items = container.querySelectorAll('.daily-notes-item');
+    expect(items).toHaveLength(3);
+    expect(items[0].textContent).toContain('2026-09-14');
+    expect(items[0].textContent).toMatch(/Sep/);
+  });
+});
+
+describe('renderDailyNotesPanel — Today button', () => {
+  test('clicking Today opens (or creates) today and calls onOpenFile with the path', async () => {
+    const openToday = jest.fn().mockResolvedValue({
+      path: '/notes/2026-09-14.md',
+      created: true,
+      content: '',
+    });
+    const onOpenFile = jest.fn();
+    const listExisting = jest.fn().mockResolvedValue(['2026-09-14.md']);
+    const { container } = mountPanel({ openToday, onOpenFile, listExisting });
+    await flush();
+
+    container.querySelector('#daily-notes-today').click();
+    await flush();
+
+    expect(openToday).toHaveBeenCalledWith({});
+    expect(onOpenFile).toHaveBeenCalledWith('/notes/2026-09-14.md');
+  });
+
+  test('shows a "Created today." / "Today already exists." status depending on the result', async () => {
+    const onOpenFile = jest.fn();
+    const { container } = mountPanel({
+      openToday: jest.fn().mockResolvedValue({ path: '/x.md', created: true }),
+      listExisting: jest.fn().mockResolvedValue([]),
+      onOpenFile,
+    });
+    await flush();
+    container.querySelector('#daily-notes-today').click();
+    await flush();
+    expect(container.querySelector('#daily-notes-status').textContent).toMatch(/Created today/);
+
+    // Re-mount with a "not created" result
+    const { container: c2 } = mountPanel({
+      openToday: jest.fn().mockResolvedValue({ path: '/x.md', created: false }),
+      listExisting: jest.fn().mockResolvedValue([]),
+      onOpenFile,
+    });
+    await flush();
+    c2.querySelector('#daily-notes-today').click();
+    await flush();
+    expect(c2.querySelector('#daily-notes-status').textContent).toMatch(/already exists/);
+  });
+
+  test('handles openToday errors gracefully (no crash, status reports)', async () => {
+    const openToday = jest.fn().mockRejectedValue(new Error('disk gone'));
+    const { container } = mountPanel({ openToday });
+    await flush();
+    container.querySelector('#daily-notes-today').click();
+    await flush();
+    expect(container.querySelector('#daily-notes-status').textContent).toMatch(/disk gone/);
+  });
+});
+
+describe('renderDailyNotesPanel — click an existing entry', () => {
+  test('clicking a row calls onOpenFile with that row\'s path', async () => {
+    const onOpenFile = jest.fn();
+    const { container } = mountPanel({
+      onOpenFile,
+      listExisting: jest.fn().mockResolvedValue([
+        '/notes/daily/2026-09-14.md',
+        '/notes/daily/2026-09-10.md',
+      ]),
+    });
+    await flush();
+    const items = container.querySelectorAll('.daily-notes-item');
+    items[1].click();
+    expect(onOpenFile).toHaveBeenCalledWith('/notes/daily/2026-09-10.md');
+  });
+
+  test('Enter / Space on a focused row opens it', async () => {
+    const onOpenFile = jest.fn();
+    const { container } = mountPanel({
+      onOpenFile,
+      listExisting: jest.fn().mockResolvedValue(['/notes/daily/2026-09-14.md']),
+    });
+    await flush();
+    const row = container.querySelector('.daily-notes-item');
+    row.focus();
+    row.dispatchEvent(new KeyboardEvent('keydown', { key: 'Enter', bubbles: true }));
+    await flush();
+    expect(onOpenFile).toHaveBeenCalledWith('/notes/daily/2026-09-14.md');
+  });
+});
+
+describe('renderDailyNotesPanel — refresh', () => {
+  test('refresh button re-fetches the list', async () => {
+    const listExisting = jest.fn().mockResolvedValueOnce([]).mockResolvedValueOnce(['2026-09-14.md']);
+    const { container, api } = mountPanel({ listExisting });
+    await flush();
+    expect(container.querySelectorAll('.daily-notes-item')).toHaveLength(0);
+
+    api.refresh();
+    await flush();
+    expect(container.querySelectorAll('.daily-notes-item')).toHaveLength(1);
+    expect(listExisting).toHaveBeenCalledTimes(2);
+  });
+});
+
+describe('renderDailyNotesPanel — graceful degradation', () => {
+  test('shows an error when listExisting rejects', async () => {
+    const listExisting = jest.fn().mockRejectedValue(new Error('ENOENT'));
+    const { container } = mountPanel({ listExisting });
+    await flush();
+    expect(container.querySelector('#daily-notes-status').textContent).toMatch(/ENOENT/);
+  });
+
+  test('shows an error when listExisting is not provided', async () => {
+    const { container } = mountPanel({ listExisting: null });
+    await flush();
+    expect(container.querySelector('#daily-notes-status').textContent).toMatch(/unavailable/);
+  });
+
+  test('filters out non-md entries', async () => {
+    const { container } = mountPanel({
+      listExisting: jest.fn().mockResolvedValue(['2026-09-14.md', 'readme.txt', '.DS_Store']),
+    });
+    await flush();
+    expect(container.querySelectorAll('.daily-notes-item')).toHaveLength(1);
+  });
+});