[12.x] Fix cache:clear command exit code on failure

[alies-dev]

Summary

The cache:clear command was returning void (which Symfony Console interprets as exit code 0) even when the cache flush operation failed. While the error message is printed to stdout, the exit code doesn't reflect the failure, which breaks the standard Unix convention that automation tools rely on.

Problem

// Before: returns void (exit code 0) even on failure
if (! $successful) {
    return $this->components->error('Failed to clear cache...');
}

The $this->components->error() method returns void, so the command exits with code 0 despite the failure. Tools can still detect failure by parsing stdout, but this is fragile compared to checking exit codes.

Solution

// After: properly returns exit code 1 on failure
if (! $successful) {
    $this->components->error('Failed to clear cache...');
    return self::FAILURE;
}

This follows the pattern used consistently in other Laravel commands like db:wipe, migrate, db:seed, etc.

Changes

• Return self::FAILURE (exit code 1) when cache flush fails
• Return self::SUCCESS (exit code 0) on successful cache clear
• Update PHPDoc return type from void to int