[grandpig]

Summary

Fix CLI configuration merging so that omitted command-line options no longer overwrite values loaded from the configuration file.

This change:

• makes --auto-nat-mode optional and applies it only when explicitly provided;
• preserves no_update and tracking_service_enable when they are enabled in the config file;
• preserves operator_address when the corresponding CLI option is omitted;
• adds regression tests covering the configuration file and CLI merge behavior.

Problem

--auto-nat-mode was defined with disabled as its CLI default, but its value was never applied to cfg.libp2p.behaviour.auto_nat_mode. As a result, passing --auto-nat-mode enabled had no effect.

Using a non-optional default would also make it impossible to distinguish an omitted CLI option from an explicit disabled value, causing configuration-file values to be overwritten.

Additionally, the following assignments always replaced values loaded from the configuration file with CLI defaults:

cfg.no_update = opts.no_update;
cfg.tracking_service_enable = opts.tracking_service_enable;
cfg.operator_address = opts.operator_address.clone();

When those options were omitted, true values were reset to false and an existing operator address was reset to None.

Fix

Change auto_nat_mode to Option and apply it only when supplied.

Use additive behavior for the enable-only boolean flags, and update the operator address only when the CLI option is present.

I have tested by the following cmd:

cargo test -p avail-light-client --bin avail-light-client
cargo test -p avail-light-client --no-default-features --bin avail-light-client
cargo clippy -p avail-light-client --no-default-features -- -D warnings

[aterentic-ethernal]

Closing PR to retrigger failing workflow by reopening it, due to missing token for test dependency fetching.