fix(frontend): SecretVault uses hardcoded mock secrets

[mrveiss]

Problem

SecretVault displays 4 hardcoded mock secrets instead of fetching from backend - users cannot add/manage real secrets.

Root Cause

Lines 39+ define hardcoded mock secrets array:

const mockSecrets: Array<SessionSecret & ...> = [
  { id: 'secret-1', name: 'GitHub API Token', ... },
  { id: 'secret-2', name: 'AWS Access Key', ... },
  { id: 'secret-3', name: 'Database Password', ... },
  { id: 'secret-4', name: 'API Key', ... },
]

Impact

• Secrets management UI is demo-only
• Cannot store/manage real credentials
• Blocks production use of secret management features

Files

• autobot-frontend/src/components/secrets/SecretVault.vue

Solution

Replace mockSecrets with API fetch from backend secret storage endpoint