feat: sortable resource tables and richer dashboard stack-health columns (#1498)

Make the Resources Images, Volumes, and Networks tables sortable with a
shared useTableSort hook and SortableTableHead, move the Images scan-history
control into the Images tab header, and keep the network List/Topology toggle
anchored with Create Network visible in both modes.

Rework the dashboard Stack health table: drop the redundant Host column, add
sortable Stack/Up/CPU/Mem headers, and add Source (local/git) and Port columns.
The status endpoint now labels each stack with its git/local source, computed
outside the cache so linking changes show immediately.

Extract a reusable CreateNetworkDialog and add a create-network action to the
stack-detail Networking tab.

frontend/src/hooks/__tests__/useTableSort.test.ts

@@ -0,0 +1,46 @@
+import { describe, it, expect } from 'vitest';
+import { renderHook, act } from '@testing-library/react';
+import { useTableSort } from '../useTableSort';
+
+interface Row { name: string; size: number }
+
+const ITEMS: Row[] = [
+  { name: 'beta', size: 30 },
+  { name: 'alpha', size: 10 },
+  { name: 'gamma', size: 20 },
+];
+
+const COMPARATORS = {
+  name: (a: Row, b: Row) => a.name.localeCompare(b.name),
+  size: (a: Row, b: Row) => a.size - b.size,
+};
+
+describe('useTableSort', () => {
+  it('sorts by the initial key and direction', () => {
+    const { result } = renderHook(() => useTableSort(ITEMS, COMPARATORS, 'name'));
+    expect(result.current.sorted.map(r => r.name)).toEqual(['alpha', 'beta', 'gamma']);
+    expect(result.current.sortKey).toBe('name');
+    expect(result.current.sortDir).toBe('asc');
+  });
+
+  it('flips direction when toggling the active key', () => {
+    const { result } = renderHook(() => useTableSort(ITEMS, COMPARATORS, 'name'));
+    act(() => result.current.toggleSort('name'));
+    expect(result.current.sortDir).toBe('desc');
+    expect(result.current.sorted.map(r => r.name)).toEqual(['gamma', 'beta', 'alpha']);
+  });
+
+  it('switches key and resets direction to asc', () => {
+    const { result } = renderHook(() => useTableSort(ITEMS, COMPARATORS, 'name', 'desc'));
+    act(() => result.current.toggleSort('size'));
+    expect(result.current.sortKey).toBe('size');
+    expect(result.current.sortDir).toBe('asc');
+    expect(result.current.sorted.map(r => r.size)).toEqual([10, 20, 30]);
+  });
+
+  it('does not mutate the input array', () => {
+    const input = [...ITEMS];
+    renderHook(() => useTableSort(input, COMPARATORS, 'size'));
+    expect(input.map(r => r.name)).toEqual(['beta', 'alpha', 'gamma']);
+  });
+});