Fix Docker/CI: reproducible Windows build, Dockerfile cleanup

- Fix Windows CI build to use npm ci instead of deleting lockfile and
  running npm install, ensuring reproducible cross-platform builds
- Remove duplicate uv/ruff root installations from Dockerfile (only
  need the claude user installations)
- Make AWS CLI install architecture-aware using uname -m for arm64
  compatibility
- Remove unused SiblingContainers component (dead code)

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

app/src/components/containers/SiblingContainers.tsx

@@ -1,67 +0,0 @@
-import { useState, useEffect, useCallback } from "react";
-import { listSiblingContainers } from "../../lib/tauri-commands";
-import type { SiblingContainer } from "../../lib/types";
-
-export default function SiblingContainers() {
-  const [containers, setContainers] = useState<SiblingContainer[]>([]);
-  const [loading, setLoading] = useState(false);
-
-  const refresh = useCallback(async () => {
-    setLoading(true);
-    try {
-      const list = await listSiblingContainers();
-      setContainers(list);
-    } catch {
-      // Silently fail
-    } finally {
-      setLoading(false);
-    }
-  }, []);
-
-  useEffect(() => {
-    refresh();
-  }, [refresh]);
-
-  return (
-    <div className="p-4">
-      <div className="flex items-center justify-between mb-3">
-        <h3 className="text-sm font-medium">Sibling Containers</h3>
-        <button
-          onClick={refresh}
-          disabled={loading}
-          className="text-xs text-[var(--text-secondary)] hover:text-[var(--text-primary)] transition-colors"
-        >
-          {loading ? "..." : "Refresh"}
-        </button>
-      </div>
-      {containers.length === 0 ? (
-        <p className="text-xs text-[var(--text-secondary)]">No other containers found.</p>
-      ) : (
-        <div className="space-y-2">
-          {containers.map((c) => (
-            <div
-              key={c.id}
-              className="px-3 py-2 bg-[var(--bg-primary)] border border-[var(--border-color)] rounded text-xs"
-            >
-              <div className="flex items-center gap-2">
-                <span
-                  className={`w-2 h-2 rounded-full flex-shrink-0 ${
-                    c.state === "running"
-                      ? "bg-[var(--success)]"
-                      : "bg-[var(--text-secondary)]"
-                  }`}
-                />
-                <span className="font-medium truncate">
-                  {c.names?.[0]?.replace(/^\//, "") ?? c.id.slice(0, 12)}
-                </span>
-              </div>
-              <div className="text-[var(--text-secondary)] mt-0.5 ml-4">
-                {c.image} — {c.status}
-              </div>
-            </div>
-          ))}
-        </div>
-      )}
-    </div>
-  );
-}