feat: SDK v0.1.8 parity - infinite sessions and client utilities

[0xeb]

Summary

• Add InfiniteSessionConfig for automatic context window compaction
• Add client utility methods: get_status(), get_auth_status(), list_models()
• Add skills configuration support (skill_directories, disabled_skills)
• Add comprehensive E2E test coverage for new features

What's New

Infinite Sessions

Automatic context window management that compacts conversation history when approaching token limits:

SessionConfig config;
config.infinite_session = InfiniteSessionConfig{
    .enabled = true,
    .truncation_strategy = "tail",
    .summarize_on_truncate = true
};

Client Utility Methods

// Get CLI version and protocol info
auto status = client.get_status().get();
std::cout << "Version: " << status.version << std::endl;

// Check authentication status
auto auth = client.get_auth_status().get();
if (auth.is_authenticated) { /* ... */ }

// List available models with capabilities
auto models = client.list_models().get();
for (const auto& model : models) {
    std::cout << model.name << " (" << model.id << ")" << std::endl;
}

Skills Configuration

SessionConfig config;
config.skill_directories = {"/path/to/skills"};
config.disabled_skills = {"dangerous-skill"};

Test Plan

• Unit tests pass (135/135)
• E2E tests for get_status, get_auth_status, list_models
• E2E tests for infinite session configuration
• Manual verification with BYOK provider

Breaking Changes

None. All changes are additive.