Unify CLI command style between `spqr-router` and `spqr-coordinator`

[Denchick]

Currently, the spqr-router binary uses a run subcommand to start, while spqr-coordinator starts directly without it. This inconsistency can be confusing for users switching between the two components.

Examples:

# Router requires 'run'
./spqr-router run -c examples/localrouter.yaml

# Coordinator starts without 'run'
./spqr-coordinator -c examples/coordinator.yaml

# Coordinator rejects 'run'
./spqr-coordinator run -c examples/coordinator.yaml
# -> Error: unknown command "run" for "spqr-coordinator"

Expected behavior: Both binaries should follow the same CLI pattern — start with run command. The coordinator binary should support backward compatibility -- start without run as well.

[vr-varad]

hey @Denchick I would like to work on this issue if its open for contribution.