fix: align cron schedule target help

[HwangJohn]

Summary

• make openwiki cron pause|resume|delete accept only all, matching the schedule mutation implementation
• update help text and examples so source-specific targets are not advertised
• add parser coverage for rejecting a source id

Testing

• corepack pnpm exec prettier --check src/commands.ts test/commands.test.ts
• corepack pnpm exec vitest run test/commands.test.ts
• corepack pnpm run lint:check
• corepack pnpm run typecheck
  Note: corepack pnpm test currently fails locally on Windows in test/env-behavior.test.ts > writes the env file with 0600 permissions (mode & 0o077 receives 54). Targeted tests above pass.