Complete the app: capture UI, dialogs, template manager, shortcuts help

- Editor topbar reworked: Back | Capture ▾ (full screen/window/region/
  delay/paste/import/session) | Save | Export | Share (.sfgz) | More ▾
  (rename, guide placeholders, backups, linked guide, shortcuts,
  settings)
- New dialogs: backups & snapshots (undoable restore), guide/global
  placeholder editor, keyboard-shortcuts reference, template manager
  (rename/duplicate/delete/share/import .sfglt)
- Export dialog: editable per-format options generated from exporter
  defaults, save-as-template, preview opens the file in the default
  viewer and keeps the dialog open for tweaking
- export:defaults IPC + preload entry
- CSS for blocks panel, focused-view sliders, export options, rows
- ipc-surface test: every preload channel has a main handler; renderer
  api.*/dialogs.* usage stays within the exposed surface (60 tests)
- CHANGELOG/README updated; prompt2.md checklist fully ticked

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

app/renderer/style.css

@@ -720,3 +720,28 @@ fieldset legend {
 .welcome-btn.primary .welcome-btn-hint { color: var(--accent-fg); }
 .welcome-btn-label { font-size: 16px; font-weight: 650; }
 .welcome-btn-hint { font-size: 12px; color: var(--muted); }
+
+/* ---------- editor additions: blocks, focused view, export options ---------- */
+.spacer { flex: 1; }
+.focused-controls {
+  margin-top: 6px;
+  padding: 8px 10px;
+  border: 1px solid var(--border);
+  border-radius: 10px;
+  background: var(--panel-2);
+  display: flex;
+  flex-direction: column;
+  gap: 4px;
+}
+.focused-controls .form-row label { width: 50px; flex: none; color: var(--muted); font-size: 12px; }
+.focused-controls input[type="range"] { flex: 1; }
+.blocks-list { display: flex; flex-direction: column; gap: 8px; margin-bottom: 8px; }
+.blocks-list .block-card textarea,
+.blocks-list .block-card input { width: 100%; }
+.blocks-list .block-card { gap: 6px; }
+.export-options { display: flex; flex-direction: column; gap: 6px; padding: 4px 2px; max-height: 260px; overflow-y: auto; }
+.placeholder-row { display: flex; gap: 8px; margin-bottom: 6px; }
+.placeholder-row input { flex: 1; }
+.card-list { display: flex; flex-direction: column; gap: 8px; }
+.card-list .row { align-items: center; }
+.row { display: flex; gap: 8px; align-items: center; }