refactor(decnet_web/CanaryTokens): move FileDropModal + LS helpers

Verbatim move of the file-drop modal (~310 LOC) and its
localStorage glue (FILEDROP_LS_KEY, FileDropEntry type,
loadFileDrops, saveFileDrops) into one file. The list view that
shows these entries lives in the page; the persistence layer
travels with the writer.

- New CanaryTokens/FileDropModal.tsx (modal + LS helpers + entry type)
- FileDropModal.test.tsx covers loadFileDrops empty / round-trip /
  200-row cap / malformed-JSON, plus modal title rendering, the
  bypass-warning banner, and CANCEL -> onClose.
- CanaryTokens.tsx loses the inline modal + LS glue plus the
  now-unused imports (useRef/X/AlertTriangle/useEscapeKey/
  useFocusTrap, plus BTN_PRIMARY/BTN_GHOST/Field that only the
  modals consumed).

decnet_web/src/components/CanaryTokens/FileDropModal.test.tsx

@@ -0,0 +1,100 @@
+import { describe, it, expect, vi, beforeEach } from 'vitest';
+import { render, screen } from '@testing-library/react';
+import userEvent from '@testing-library/user-event';
+import {
+  FileDropModal, loadFileDrops, saveFileDrops,
+  FILEDROP_LS_KEY, type FileDropEntry,
+} from './FileDropModal';
+import type { DeckyOption, TopologyOption } from './types';
+
+vi.mock('../../hooks/useFocusTrap', () => ({ useFocusTrap: () => {} }));
+
+const deckies: DeckyOption[] = [{ name: 'decoy-01' }];
+const topologies: TopologyOption[] = [{ id: 't-1', name: 'corp', status: 'active' }];
+
+beforeEach(() => {
+  localStorage.clear();
+});
+
+const sampleEntry = (): FileDropEntry => ({
+  id: 'fd-1',
+  decky_name: 'd',
+  topology_id: null,
+  path: '/tmp/x',
+  size_bytes: 1,
+  filename: 'x',
+  mode: 0o644,
+  mtime_offset: 0,
+  dropped_at: '2026-05-09T11:00:00Z',
+});
+
+describe('loadFileDrops / saveFileDrops', () => {
+  it('returns [] when localStorage is empty', () => {
+    expect(loadFileDrops()).toEqual([]);
+  });
+
+  it('round-trips through localStorage', () => {
+    saveFileDrops([sampleEntry()]);
+    const out = loadFileDrops();
+    expect(out).toHaveLength(1);
+    expect(out[0].id).toBe('fd-1');
+  });
+
+  it('caps to 200 entries on save', () => {
+    const many: FileDropEntry[] = Array.from({ length: 250 }, (_, i) => ({
+      ...sampleEntry(), id: `fd-${i}`,
+    }));
+    saveFileDrops(many);
+    const stored = JSON.parse(localStorage.getItem(FILEDROP_LS_KEY) ?? '[]');
+    expect(stored).toHaveLength(200);
+  });
+
+  it('returns [] on malformed JSON in storage', () => {
+    localStorage.setItem(FILEDROP_LS_KEY, '{not-an-array');
+    expect(loadFileDrops()).toEqual([]);
+  });
+});
+
+describe('FileDropModal', () => {
+  it('renders the title and the Fleet/MazeNET toggle', () => {
+    render(
+      <FileDropModal
+        deckies={deckies}
+        topologies={topologies}
+        onClose={() => {}}
+        onDropped={() => {}}
+      />,
+    );
+    expect(screen.getByText('DROP FILE ON DECKY')).toBeInTheDocument();
+    expect(screen.getByText('Fleet')).toBeInTheDocument();
+  });
+
+  it('renders the bypass-warning banner', () => {
+    render(
+      <FileDropModal
+        deckies={deckies}
+        topologies={topologies}
+        onClose={() => {}}
+        onDropped={() => {}}
+      />,
+    );
+    expect(
+      screen.getByText(/File drops bypass canary instrumentation/),
+    ).toBeInTheDocument();
+  });
+
+  it('CANCEL invokes onClose', async () => {
+    const onClose = vi.fn();
+    const user = userEvent.setup();
+    render(
+      <FileDropModal
+        deckies={deckies}
+        topologies={topologies}
+        onClose={onClose}
+        onDropped={() => {}}
+      />,
+    );
+    await user.click(screen.getByText('CANCEL'));
+    expect(onClose).toHaveBeenCalled();
+  });
+});