feat(docker): one-click "Run in Docker" case creation + Export button

- New POST /api/cases/docker-quickcreate: creates a normal case (folder in
  CASES_DIR, scaffolded CLAUDE.md + hooks) AND links it to a hardened container
  with default settings, auto-provisioning a shared `default` docker host — the
  user never touches host/image/network fields.
- Create New tab gains a "Run in isolated Docker container" checkbox; on submit it
  calls docker-quickcreate then auto-starts a claude session inside the container.
- Case Manage list gains an Export (full-image) button per docker case.
- SSE listeners for docker:exportComplete/exportFailed toast + refresh the exports
  list.

Verified end-to-end on the live instance: one-click create put the case in
~/codeman-cases/<name>, auto-created the default host, launched claude in the
container; export button produces a bundle; checkbox + button render (Playwright).

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

src/web/public/app.js

@@ -1433,6 +1433,25 @@ class CodemanApp {
     for (const event of [SSE_EVENTS.SESSION_CREATED, SSE_EVENTS.SESSION_DELETED]) {
       addListener(event, () => this._onSessionListMaybeChanged());
     }
+
+    // Docker export/import: toast + refresh the Manage-tab exports list on completion.
+    addListener(SSE_EVENTS.DOCKER_EXPORT_COMPLETE, (e) => {
+      try {
+        const d = e.data ? JSON.parse(e.data) : {};
+        this.showToast(`Docker export ready: ${d.bundle} (${Math.round((d.sizeBytes || 0) / 1e6)} MB)`, 'success');
+        this.refreshDockerExports?.();
+      } catch (err) {
+        console.error('[SSE] docker export complete:', err);
+      }
+    });
+    addListener(SSE_EVENTS.DOCKER_EXPORT_FAILED, (e) => {
+      try {
+        const d = e.data ? JSON.parse(e.data) : {};
+        this.showToast(`Docker export failed: ${d.error || 'unknown error'}`, 'error');
+      } catch (err) {
+        console.error('[SSE] docker export failed:', err);
+      }
+    });
   }
 
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