Add network map UX and theme support.

Introduce network map view/components with filtering and positioning, expand contacts/map backend fields and migrations, and add a persistent light/dark theme toggle with graph label color updates for readability.

Co-authored-by: Cursor <cursoragent@cursor.com>

frontend/src/lib/api/errors.test.js

@@ -0,0 +1,15 @@
+import { describe, it, expect } from 'vitest'
+import { normalizeApiError } from './errors'
+
+describe('normalizeApiError', () => {
+  it('extracts API message from response payload', () => {
+    const err = normalizeApiError({ response: { status: 400, data: { error: 'Bad request' } } })
+    expect(err.message).toBe('Bad request')
+    expect(err.status).toBe(400)
+  })
+
+  it('falls back to generic message', () => {
+    const err = normalizeApiError({})
+    expect(err.message.length).toBeGreaterThan(0)
+  })
+})