Initial commit: Triple-C app, container, and CI

Tauri v2 desktop app (React/TypeScript + Rust) for managing
containerized Claude Code environments. Includes Gitea Actions
workflow for building and pushing the sandbox container image,
and a BUILDING.md guide for manual app builds on Linux and Windows.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

app/src/components/layout/Sidebar.tsx

@@ -0,0 +1,40 @@
+import { useAppState } from "../../store/appState";
+import ProjectList from "../projects/ProjectList";
+import SettingsPanel from "../settings/SettingsPanel";
+
+export default function Sidebar() {
+  const { sidebarView, setSidebarView } = useAppState();
+
+  return (
+    <div className="flex flex-col h-full w-64 bg-[var(--bg-secondary)] border border-[var(--border-color)] rounded-lg overflow-hidden">
+      {/* Nav tabs */}
+      <div className="flex border-b border-[var(--border-color)]">
+        <button
+          onClick={() => setSidebarView("projects")}
+          className={`flex-1 px-3 py-2 text-sm font-medium transition-colors ${
+            sidebarView === "projects"
+              ? "text-[var(--accent)] border-b-2 border-[var(--accent)]"
+              : "text-[var(--text-secondary)] hover:text-[var(--text-primary)]"
+          }`}
+        >
+          Projects
+        </button>
+        <button
+          onClick={() => setSidebarView("settings")}
+          className={`flex-1 px-3 py-2 text-sm font-medium transition-colors ${
+            sidebarView === "settings"
+              ? "text-[var(--accent)] border-b-2 border-[var(--accent)]"
+              : "text-[var(--text-secondary)] hover:text-[var(--text-primary)]"
+          }`}
+        >
+          Settings
+        </button>
+      </div>
+
+      {/* Content */}
+      <div className="flex-1 overflow-y-auto">
+        {sidebarView === "projects" ? <ProjectList /> : <SettingsPanel />}
+      </div>
+    </div>
+  );
+}